{ "reviewed": "2026-10-01", "scope": "Educational gasoline passenger vehicle. Simplified geometry, approximate locations, vehicle-specific confirmation required. Driver quotations are illustrative.", "sources": [ { "id": "pt-pistons", "title": "Piston damage: increased oil consumption", "url": "https://www.ms-motorservice.com/sg/en/technipedia/piston-damage-1518", "publisher": "Motorservice" }, { "id": "pt-bearings", "title": "Damage to engine bearings", "url": "https://www.ms-motorservice.com/MediaAssets/damage-to-engine-bearings_861097.pdf", "publisher": "Motorservice" }, { "id": "pt-valves", "title": "Valve damage and causes", "url": "https://www.ms-motorservice.com/int/en/technipedia/valve-damage-and-causes-305", "publisher": "Motorservice" }, { "id": "pt-oilpump", "title": "Function of a variable oil pump", "url": "https://www.ms-motorservice.com/int/en/technipedia/function-of-a-variable-oil-pump-1172", "publisher": "Motorservice" }, { "id": "pt-oilpressure", "title": "Oil pressure and oil level sensors", "url": "https://www.ms-motorservice.com/MediaAssets/oil-pressure-and-oil-level-sensors-for-optimum-engine-oil-supply_3084494.pdf", "publisher": "Motorservice" }, { "id": "pt-filters", "title": "Engine components and filters failure guide", "url": "https://www.mahle-aftermarket.com/media/local-media-north-america/pdfs-&-thumbnails/mahle-engine-component-&-filters-failure-guide.pdf", "publisher": "MAHLE" }, { "id": "pt-belt", "title": "Timing 101", "url": "https://go.gates.com/timing101", "publisher": "Gates" }, { "id": "pt-chain", "title": "Comprehensive guide to timing chain replacement", "url": "https://www.gatestechzone.com/en/news/2025-06-chain-maintenance", "publisher": "Gates" }, { "id": "pt-pcv", "title": "The role of the positive crankcase ventilation valve", "url": "https://www.gatestechzone.com/en/news/2021-06-positive-crankcase-ventilation", "publisher": "Gates" }, { "id": "pt-mechanical", "title": "Mityvac manual: diagnosing mechanical engine conditions", "url": "https://cdn.skfmediahub.skf.com/api/public/0901d196809b1436/pdf_preview_medium/0901d196809b1436_pdf_preview_medium.pdf", "publisher": "SKF / Mityvac" }, { "id": "pt-lockup", "title": "Troubleshooting lockup issues", "url": "https://www.sonnax.com/tech_resources/97-troubleshooting-lockup-issues", "publisher": "Sonnax" }, { "id": "pt-transpump", "title": "Anatomy of a transmission: pump, converter and cooler oil flow", "url": "https://www.sonnax.com/tech_resources/131-anatomy-of-a-transmission-oil-flow-in-the-pump-pr-converter-cooler-lube-circuits", "publisher": "Sonnax" }, { "id": "pt-transdiagnosis", "title": "CD4E transmission diagnostic checklist", "url": "https://www.sonnax.com/tech_resources/241-cd4e-transmission-inspection-checklist", "publisher": "Sonnax" }, { "id": "pt-clutchpacks", "title": "Rebuild tips for 4L60/E clutch burnup", "url": "https://www.sonnax.com/tech_resources/659-all-over-the-map-attacking-4l60-e-burnt-3-4-clutches-with-confidence", "publisher": "Sonnax" }, { "id": "pt-transspeed", "title": "Transmission sensor circuit and speed sensing", "url": "https://www.hella.com/techworld/en/technical/sensors-and-actuators/transmission-range-sensor-circuit/", "publisher": "HELLA" }, { "id": "pt-transcooler", "title": "Automatic transmission oil coolers", "url": "https://www.hella.com/techworld/en/car-parts/thermal-management/ec-automatic-transmission-oil/", "publisher": "HELLA" }, { "id": "pt-clutch", "title": "Clutch slipping", "url": "https://aftermarket.zf.com/en/aftermarket-portal/knowledge-hub/clutch-slipping/", "publisher": "ZF / SACHS" }, { "id": "pt-release", "title": "Clutch does not disengage", "url": "https://aftermarket.zf.com/en/aftermarket-portal/knowledge-hub/clutch-does-not-disengage/", "publisher": "ZF / SACHS" }, { "id": "pt-dmf", "title": "Dual-mass flywheel noises and surrounding faults", "url": "https://aftermarket.zf.com/app/controller/ti/download/Binary/b3a61f70-1004-11ec-a2de-00505690da53.pdf", "publisher": "ZF / SACHS" }, { "id": "pt-fuelpressure", "title": "Testing fuel pressure and flow", "url": "https://www.delphiautoparts.com/resource-center/article/4-steps-on-how-to-test-fuel-pressure-and-flow", "publisher": "Delphi" }, { "id": "pt-fuelvoltage", "title": "Fuel pump voltage drop testing", "url": "https://www.delphiautoparts.com/resource-center/article/how-to-perform-a-voltage-drop-test", "publisher": "Delphi" }, { "id": "pt-highpump", "title": "Checking a high-pressure fuel pump", "url": "https://www.hella.com/techworld/us/technical/sensors-and-actuators/checking-a-high-pressure-fuel-pump/", "publisher": "HELLA" }, { "id": "pt-injector", "title": "Injection valve function, symptoms and checks", "url": "https://www.hella.com/techworld/en/technical/sensors-and-actuators/injection-nozzle/", "publisher": "HELLA" }, { "id": "pt-fuelfilter", "title": "Fuel filter function and blockage symptoms", "url": "https://www.delphiautoparts.com/en-gb/products-and-technologies/gasoline-fuel-systems/fuel-management-system/fuel-modules-and-pumps/how-to-replace-your-fuel-filter", "publisher": "Delphi" }, { "id": "pt-maf", "title": "Making sense of your sensors: MAF sensor", "url": "https://www.delphiautoparts.com/en-gb/products-and-technologies/vehicle-electronics-engine-management/sensors/mass-air-flow-sensors/making-sense-of-your-sensors-maf-sensor", "publisher": "Delphi" }, { "id": "pt-map", "title": "Making sense of your sensors: MAP sensor", "url": "https://www.delphiautoparts.com/resource-center/article/making-sense-of-your-sensors-map-sensor", "publisher": "Delphi" }, { "id": "pt-airfilter", "title": "Engine air filters protect engine life and performance", "url": "https://www.mann-filter.com/ca-en/parts/air-filter.html", "publisher": "MANN-FILTER" }, { "id": "pt-manifold", "title": "All about intake manifold gaskets", "url": "https://www.felpro.com/gaskets-101/all-about-intake-manifold-gaskets.html", "publisher": "Fel-Pro" }, { "id": "pt-leaks", "title": "Leak inspection checklist", "url": "https://www.felpro.com/content/dam/marketing/North-America/felpro/pdfs/Fel-Pro-Leak-Inspection-Checklist.pdf", "publisher": "Fel-Pro" }, { "id": "pt-waterpump", "title": "Water pump failure signs", "url": "https://www.gatestechzone.com/en/problem-diagnosis/cooling-system/water-pump-failure-signs", "publisher": "Gates" }, { "id": "pt-radiator", "title": "Radiator function and replacement indicators", "url": "https://www.hella.com/forvia-us/assets/documents/BI_Thermal_Management_Radiator_2026.pdf", "publisher": "HELLA" }, { "id": "pt-thermostat", "title": "Thermostat failure signs", "url": "https://www.gatestechzone.com/en/problem-diagnosis/cooling-system/thermostat-failure-signs", "publisher": "Gates" }, { "id": "pt-fan", "title": "Radiator fans: function and fault symptoms", "url": "https://www.hella.com/forvia-us/assets/documents/BI_Thermal_Management_Radiator_Fans_2026.pdf", "publisher": "HELLA" }, { "id": "pt-coolingchecks", "title": "Cooling system checks and diagnostics", "url": "https://www.hella.com/techworld/en/technical/car-cooling-system/cooling-system-check/", "publisher": "HELLA" }, { "id": "pt-hoses", "title": "Coolant hose failure symptoms", "url": "https://www.gatestechzone.com/en/problem-diagnosis/cooling-system/hose-failure-symptoms", "publisher": "Gates" }, { "id": "pt-tank", "title": "Coolant expansion tanks", "url": "https://www.hella.com/techworld/us/passenger-car-parts/thermal-management/ec-expansion-tanks/", "publisher": "HELLA" }, { "id": "pt-cap", "title": "Radiator and expansion tank cap function test", "url": "https://www.gatestechzone.com/en/problem-diagnosis/cooling-system/cap-function-test", "publisher": "Gates" }, { "id": "pt-coolantsensor", "title": "Coolant temperature sensor testing", "url": "https://www.hella.com/techworld/us/technical/sensors-and-actuators/test-coolant-temperature-sensor/", "publisher": "HELLA" }, { "id": "pt-heater", "title": "How heater cores work", "url": "https://www.denso-am.eu/products/ac-engine-cooling/heater-cores", "publisher": "DENSO" }, { "id": "pt-headgasket", "title": "Driving with a blown head gasket", "url": "https://www.felpro.com/gaskets-101/can-you-drive-your-vehicle-with-a-blown-head-gasket.html", "publisher": "Fel-Pro" }, { "id": "pt-headcrack", "title": "Cracked head versus blown head gasket", "url": "https://www.felpro.com/technical/tecblogs/Cracked-Head-vs-Blown-Head-Gasket.html", "publisher": "Fel-Pro" }, { "id": "pt-plugs", "title": "Spark plug basics", "url": "https://ngksparkplugs.com/en/resources/spark-plug-basics", "publisher": "NGK" }, { "id": "pt-coils", "title": "Ignition coils, leads and caps questions answered", "url": "https://www.ngkntk.com/ae/newsroom/blog/emea/you-asked-google-ngk-spark-plug-answers-part-4-ignition-coils-leads-caps/", "publisher": "NGK / Niterra" }, { "id": "pt-crank", "title": "Crankshaft sensor function and diagnosis", "url": "https://www.hella.com/techworld/en/technical/sensors-and-actuators/crankshaft-sensor/", "publisher": "HELLA" }, { "id": "pt-cam", "title": "Camshaft sensor function and diagnosis", "url": "https://www.hella.com/techworld/au/technical/sensors-and-actuators/camshaft-position-sensor/", "publisher": "HELLA" }, { "id": "pt-knock", "title": "Knock sensor function and diagnosis", "url": "https://www.hella.com/techworld/en/technical/sensors-and-actuators/car-knock-sensor-mdash-function-and-troubleshooting/", "publisher": "HELLA" }, { "id": "pt-throttle", "title": "What is an electronic throttle body?", "url": "https://www.aftermarket.astemo.com/apac/en/news/2026/0724_004954.html", "publisher": "Astemo" }, { "id": "pt-tps", "title": "Throttle position sensor function and diagnosis", "url": "https://www.hella.com/techworld/uk/technical/sensors-and-actuators/throttle-potentiometer/", "publisher": "HELLA" }, { "id": "pt-pedal", "title": "Accelerator pedal sensor function and diagnosis", "url": "https://www.hella.com/techworld/en/technical/sensors-and-actuators/accelerator-pedal-sensor/", "publisher": "HELLA" }, { "id": "pt-warning", "title": "Owner manual: oil pressure and coolant temperature warnings", "url": "https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?ProcUid=G1748789&Uid=G1748786&buildtype=web&countryCode=USA&div=f&languageCode=EN&userMarket=ZAF&vCode=&vFilteringEnabled=False&variantid=3751", "publisher": "Ford" }, { "id": "pt-misfire", "title": "Owner manual: flashing engine warning and misfire", "url": "https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?ProcUid=G1661171&Uid=G1644848&buildtype=web&countryCode=USA&div=f&languageCode=en&vFilteringEnabled=True&variantid=3326", "publisher": "Ford" }, { "id": "pt-valvebody", "title": "6T30/40/45/50 valve-body pressure-loss diagnosis", "url": "https://www.sonnax.com/parts/3792-zip-kit", "publisher": "Sonnax" }, { "id": "pt-coilcheck", "title": "Ignition coil function, symptoms and professional diagnosis", "url": "https://www.hella.com/techworld/uk/technical/car-electronics-and-electrics/check-ignition-coil/", "publisher": "HELLA" }, { "id": "pt-wire", "title": "Ignition wire sets basics", "url": "https://ngksparkplugs.com/en/resources/wire-sets-basics", "publisher": "NGK" }, { "id": "pt-plugwear", "title": "Spark plug wear and fault diagnosis", "url": "https://www.denso-am.eu/news/dont-overlook-spark-plug-replacement-reminds-denso", "publisher": "DENSO" }, { "id": "pt-fuelleaksafety", "title": "What to do if a vehicle is leaking fuel", "url": "https://www.ford.co.th/en/support/how-tos/more-vehicle-topics/fuel-and-fuel-economy/what-should-be-done-if-a-vehicle-is-leaking-fuel", "publisher": "Ford" }, { "id": "pt-coolantsafety", "title": "Owner manual: coolant safety and overheating", "url": "https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?ProcUid=G1603551&Uid=G1448631&buildtype=web&countryCode=USA&div=f&languageCode=en&userMarket=usa&vFilteringEnabled=False&variantid=3712", "publisher": "Ford" }, { "id": "ch-tpms-types", "title": "HELLA TPMS sensors: precise monitoring, fast installation", "url": "https://www.hella.com/techworld/uk/car-parts/auto-electronics/reifendrucksensor/", "publisher": "HELLA" }, { "id": "ch-cv-service", "title": "CV Do's and Don'ts, PT60-0004", "url": "https://www.cardone.com/content/Products/PT60-0004.pdf", "publisher": "CARDONE" }, { "id": "ch-cv-axles", "title": "What is a CV Axle?", "url": "https://www.moogparts.com/parts-matter/What-is-a-CV-Axle.html", "publisher": "MOOG" }, { "id": "ch-cv-noise", "title": "Top 5 Noise Symptoms Associated With A Worn CV Shaft, TB0217", "url": "https://www.trakmotive.com/wp-content/uploads/2017/02/TrakMotive-Noise-Sumptoms-of-a-Worn-CV-Shaft-02.17.pdf", "publisher": "TrakMotive" }, { "id": "ch-steering-pump", "title": "Hydraulic steering pump: function and repair instructions", "url": "https://www.hella.com/techworld/uk/technical/car-electronics-and-electrics/hydraulic-steering-pump/", "publisher": "HELLA" }, { "id": "ch-slide-pins", "title": "Floating calliper guide pins: practical repair tips", "url": "https://www.hella.com/techworld/uk/technical/brakes/floating-calliper-guide-pins/", "publisher": "HELLA" }, { "id": "ch-handbrake-cable", "title": "Changing the handbrake cable using a Mazda as an example", "url": "https://www.hella.com/techworld/uk/technical/brakes/replace-handbrake-cable/", "publisher": "HELLA" }, { "id": "ch-pads", "title": "How can I tell if my brake pads are worn?", "url": "https://www.bremboparts.com/europe/en/support/car/maintenance/how-can-i-tell-if-my-brake-pads-are-worn-335458", "publisher": "Brembo" }, { "id": "ch-rotors", "title": "Minimum brake disc thickness", "url": "https://www.bremboparts.com/asiapacific/en/support/car/maintenance/minimum-brake-disc-thickness-212337", "publisher": "Brembo" }, { "id": "ch-brake-noise", "title": "Noises and vibrations", "url": "https://www.bremboparts.com/europe/is/support/car/maintenance/noises-and-vibrations-113941", "publisher": "Brembo" }, { "id": "ch-calipers", "title": "Repair kits for brake calipers", "url": "https://asia.bremboparts.com/europe/en/support/car/insights/repair-kits-for-brake-calipers-207813", "publisher": "Brembo" }, { "id": "ch-caliper-check", "title": "Tech Check: Brake Calipers", "url": "https://www.cardone.com/content/Products/931107-18DE%20Brake%20Calipers%20Digital%20English.pdf", "publisher": "CARDONE" }, { "id": "ch-lines", "title": "Brake hoses and brake lines", "url": "https://www.hella.com/techworld/au/ti/brake-hoses-and-brake-lines/", "publisher": "HELLA" }, { "id": "ch-hoses", "title": "Brake Hoses", "url": "https://www.delphiautoparts.com/en-gb/products-and-technologies/braking-steering-suspension/braking/brake-hoses", "publisher": "Delphi" }, { "id": "ch-master", "title": "Brake Hose May Cause Low Pedal, PT10-0005", "url": "https://www.cardone.com/content/Products/PT10-0005.pdf", "publisher": "CARDONE" }, { "id": "ch-booster", "title": "Diagnosing a Vacuum Brake Booster, PT54-0006", "url": "https://www.cardone.com/content/Products/PT54-0006.pdf", "publisher": "CARDONE" }, { "id": "ch-vacuum", "title": "Testing an electric vacuum pump", "url": "https://www.hella.com/techworld/uk/technical/car-electronics-and-electrics/testing-an-electric-vacuum-pump/", "publisher": "HELLA" }, { "id": "ch-fluid", "title": "Brake fading and vapour lock: two problems compared", "url": "https://www.bremboparts.com/europe/en/support/car/maintenance/brake-fading-and-vapour-lock-two-problems-compared-324324", "publisher": "Brembo" }, { "id": "ch-speed-sensors", "title": "Check and change ABS and wheel speed sensors", "url": "https://www.hella.com/techworld/uk/technical/sensors-and-actuators/check-and-change-abs-and-wheel-speed-sensors/", "publisher": "HELLA" }, { "id": "ch-abs", "title": "ABS and ESP control units: Function, diagnosis and repair instructions", "url": "https://www.hella.com/techworld/uk/technical/car-electronics-and-electrics/abs-esp-control-units-for-braking-and-driving-dynamics/", "publisher": "HELLA" }, { "id": "ch-parking", "title": "Electric Park Brake, XZM200GB", "url": "https://aftermarket.zf.com/en/media/master/downloads/xzm200.pdf", "publisher": "ZF Aftermarket / TRW" }, { "id": "ch-steering-diagnosis", "title": "Symptoms of bad steering and suspension", "url": "https://www.delphiautoparts.com/products-technologies/braking-steering-suspension/steering-suspension/chassis/ball-joints/symptoms-of-bad-steering-and-suspension", "publisher": "Delphi" }, { "id": "ch-eps-rack", "title": "Tech Check: Electronic Power Steering", "url": "https://www.cardone.com/content/Products/931140-1ADE%20Electronic%20Power%20Steering%20Digital%20English.pdf", "publisher": "CARDONE" }, { "id": "ch-eps", "title": "EPS Symptoms and Solutions, PT1A-0005", "url": "https://www.cardone.com/content/Products/PT1A-0005.pdf", "publisher": "CARDONE" }, { "id": "ch-steering-sensors", "title": "Steering torque and angle sensor", "url": "https://www.hella.com/microsite-electronics/en/Steering-torque-and-angle-sensors-512.html", "publisher": "HELLA" }, { "id": "ch-inner-tie", "title": "Product Test: MOOG Axial Rod", "url": "https://www.moogparts.com/content/dam/marketing/emea/moog/pdf/competitor-tests/Competitor-Test-Axial-Rod.pdf", "publisher": "MOOG" }, { "id": "ch-outer-tie", "title": "Symptoms of Bad Tie Rods", "url": "https://www.moogparts.com/parts-matter/symptoms-of-bad-tie-rods.html", "publisher": "MOOG" }, { "id": "ch-steering-column", "title": "Ford safety recall 13S08: Lower intermediate steering shaft corrosion", "url": "https://static.nhtsa.gov/odi/rcl/2013/RCDNN-13V385-2210.pdf", "publisher": "Ford Motor Company, hosted by NHTSA" }, { "id": "ch-hydraulic-steering", "title": "Power Steering System Diagnostic Chart, PT20-0034", "url": "https://www.cardone.com/content/Products/PT20-0034.pdf", "publisher": "CARDONE" }, { "id": "ch-ball-joints", "title": "Symptoms of Bad Ball Joints", "url": "https://www.moogparts.com/parts-matter/symptoms-of-bad-ball-joints.html", "publisher": "MOOG" }, { "id": "ch-control-arms", "title": "Signs and Symptoms of a Failing Control Arm", "url": "https://www.moogparts.com/parts-matter/Signs-of-a-Failing-Control-Arm.html", "publisher": "MOOG" }, { "id": "ch-arm-bushings", "title": "Troubleshooting Vertical Control Arm Bushing Failure", "url": "https://www.moogparts.com/technical/bulletins/tech-tips/troubleshooting-vertical-control-arm-bushing-failure.html", "publisher": "MOOG" }, { "id": "ch-sway-links", "title": "Signs of Bad Sway Bar Links", "url": "https://www.moogparts.com/parts-matter/Symptoms-of-Bad-Sway-Bar-Links.html", "publisher": "MOOG" }, { "id": "ch-sway-bushings", "title": "Problem Solver Sway Bar Bushing", "url": "https://www.moogparts.com/parts/suspension/vehicle-bushings/sway-bar-bushings.html", "publisher": "MOOG" }, { "id": "ch-strut-mounts", "title": "Diagnosing Noise With New Shocks and Struts", "url": "https://www.monroe.com/technical-resources/tech-tips/diagnosing-noise-with-new-shock-struts.html", "publisher": "Monroe" }, { "id": "ch-springs", "title": "What Every Technician Needs to Know About Coil Springs", "url": "https://www.monroe.com/technical-resources/tech-tips/What-Every-Technician-Needs-to-Know-About-Coil-Springs.html", "publisher": "Monroe" }, { "id": "ch-protection", "title": "Maximize the life and performance of new shock absorbers", "url": "https://www.monroe.com/sr-rs/support/technical-tips/lv/mounting-kits-protection-kits/always-install-new-protection-kits.html", "publisher": "Monroe" }, { "id": "ch-shocks", "title": "Monroe Shock Absorbers Master Catalogue: Symptoms of physical wear", "url": "https://www.monroe.com/content/dam/marketing/emea/monroe/support/catalogues/monroe-shock-absorbers-catalogue.pdf", "publisher": "Monroe" }, { "id": "ch-shock-leaks", "title": "Weepage vs Leakage in Shocks and Struts", "url": "https://aftermarket.monroe.com/technical-resources/servicegrams/weepage-vs-leakage-shocks-struts.html", "publisher": "Monroe" }, { "id": "ch-bearings", "title": "Symptoms of a Worn Wheel Hub Bearing, LV5", "url": "https://www.timken.com/wp-content/uploads/2017/08/LV5-Symptoms-of-a-Worn-Wheel-Hub-Bearing.pdf", "publisher": "Timken" }, { "id": "ch-hubs", "title": "Wheel Hub Damage Analysis Guide, LV7", "url": "https://www.timken.com/pl/resources/lv7-wheel-hub-damage-analysis-guide/", "publisher": "Timken" }, { "id": "ch-tires", "title": "Tire damages", "url": "https://www.continental-tires.com/tire-knowledge/tire-damages/", "publisher": "Continental" }, { "id": "ch-sidewalls", "title": "Sidewall Problems", "url": "https://www.michelinman.com/auto/auto-tips-and-advice/tire-damage/sidewall-problems", "publisher": "Michelin" }, { "id": "ch-rim-leaks", "title": "Tire repair", "url": "https://www.continental-tires.com/tire-knowledge/tire-repair/", "publisher": "Continental" }, { "id": "ch-tire-care", "title": "Routine Tire Care Tips", "url": "https://www.michelinman.com/auto/auto-tips-and-advice/tire-maintenance/routine-tire-care-tips", "publisher": "Michelin" }, { "id": "ch-tpms", "title": "Step-by-Step Best Practices in TPMS", "url": "https://www.schradertpms.com/sites/default/files/2024-10/TPMS_Best_Practices.pdf", "publisher": "Schrader TPMS Solutions" }, { "id": "ch-fasteners", "title": "Changing a Road Wheel: Wheel Nuts", "url": "https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?ProcUid=G2227314&Uid=G2267322&buildtype=web&countryCode=USA&div=f&languageCode=en&moidRef=G2154962&userMarket=usa&vFilteringEnabled=False&variantid=10789", "publisher": "Ford Motor Company" }, { "id": "ch-wheel-vibration", "title": "Symptom: Vibration or Shimmy", "url": "https://www.michelinman.com/auto/auto-tips-and-advice/tire-damage/handling-problems/symptom-vibration", "publisher": "Michelin" }, { "id": "ch-cv-inspection", "title": "SPIDAN Workshop Tips: How to identify driveshaft damages", "url": "https://www.gknautomotive.com/media/jtgleypo/workshop_tips_spidan_cv_gb.pdf", "publisher": "GKN Automotive" }, { "id": "ch-cv-joints", "title": "Constant velocity joints", "url": "https://www.gknautomotive.com/en/aftermarket/portfolio/constant-velocity-joints/", "publisher": "GKN Automotive" }, { "id": "ch-cv-boots", "title": "Driveshaft boots", "url": "https://www.gknautomotive.com/en/aftermarket/portfolio/driveshaft-boots/", "publisher": "GKN Automotive" }, { "id": "ch-sideshafts", "title": "Sideshafts", "url": "https://www.gknautomotive.com/en/aftermarket/portfolio/sideshafts/", "publisher": "GKN Automotive" }, { "id": "ch-propshafts", "title": "Propshafts", "url": "https://www.gknautomotive.com/en/products-and-systems/propshafts/", "publisher": "GKN Automotive" }, { "id": "ch-u-joints", "title": "How to Tell If You Have a Bad Universal Joint", "url": "https://www.moogparts.com/parts-matter/How-to-Tell-If-You-Have-a-Bad-Universal-Joint.html", "publisher": "MOOG" }, { "id": "ch-center-bearing", "title": "Mancal central tem que ser Spicer! (Propshaft center supports)", "url": "https://dana.com.br/mancal-central-tem-que-ser-spicer/", "publisher": "Dana" }, { "id": "ch-differential", "title": "Problemas na dirigibilidade? Pode ser o diferencial traseiro (Rear differential symptoms)", "url": "https://dana.com.br/problemas-na-dirigibilidade-pode-ser-o-diferencial-traseiro/", "publisher": "Dana" }, { "id": "ch-differential-service", "title": "Cuidados no reparo do eixo diferencial (Differential repair considerations)", "url": "https://dana.com.br/cuidados-no-reparo-do-eixo-diferencial/", "publisher": "Dana" }, { "id": "ch-axle-seals", "title": "Dana explica quando e hora de substituir a vedacao nos eixos diferenciais (Differential seal symptoms)", "url": "https://dana.com.br/dana-explica-quando-e-hora-de-substituir-a-vedacao-nos-eixos-diferenciais/", "publisher": "Dana" }, { "id": "el-start-tests", "title": "Starter troubleshooting", "url": "https://www.denso-am.eu/news/starter-troubleshooting", "publisher": "DENSO" }, { "id": "el-starter", "title": "High Performance Starters: installation and fault finding", "url": "https://www.denso-am.eu/products/rotating-electrics/starter", "publisher": "DENSO" }, { "id": "el-alternator", "title": "Diagnosing Alternator Faults the Right Way", "url": "https://www.denso-am.eu/news/denso-techtip-diagnosing-alternator-faults-the-right-way", "publisher": "DENSO" }, { "id": "el-battery", "title": "Car Batteries: identifying a faulty battery", "url": "https://www.interstatebatteries.com/car-and-truck-batteries", "publisher": "Interstate Batteries" }, { "id": "el-battery-causes", "title": "Battery FAQs: repeated discharge and testing", "url": "https://www.interstatebatteries.com/en-ca/support/faqs", "publisher": "Interstate Batteries" }, { "id": "el-ground", "title": "Alternators: troubleshooting ground connections", "url": "https://www.hella.com/forvia-us/assets/documents/BI_Alternators_2026.pdf", "publisher": "FORVIA HELLA" }, { "id": "el-fuses", "title": "2024 F-150 Owner's Manual: Fuse Precautions", "url": "https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?ProcUid=G2131800&Uid=G2131797&buildtype=web&countryCode=USA&div=f&languageCode=en&moidRef=G2130734&userMarket=USA&vFilteringEnabled=False&variantid=9535", "publisher": "Ford" }, { "id": "el-belt", "title": "Tensioner 101: accessory belt drive system", "url": "https://go.gates.com/tensioner101", "publisher": "Gates" }, { "id": "el-tensioner", "title": "Diagnosing Tensioner Failure, Bulletin TT004-15", "url": "https://www.gates.com/content/dam/documents-library/tech-tips-bulletins/tt004-15.pdf", "publisher": "Gates" }, { "id": "el-catalyst", "title": "Diagnosing Catalytic Converter Issues", "url": "https://www.walkerexhaust.com/support/tech-tips/diagnosing-catalytic-converter-issues.html", "publisher": "Walker Exhaust" }, { "id": "el-oxygen", "title": "How lambda sensors work", "url": "https://www.denso-am.eu/products/engine-management-systems/lambda-sensors", "publisher": "DENSO" }, { "id": "el-oxygen-tests", "title": "Lambda Sensor fault-finding", "url": "https://www.denso-am.eu/news/october-2017-lambda-sensor-fault-finding-helps-deliver-outstanding-customer-service", "publisher": "DENSO" }, { "id": "el-leaks", "title": "Signs of an Exhaust Leak", "url": "https://www.walkerexhaust.com/support/exhaust-101/signs-of-an-exhaust-leak.html", "publisher": "Walker Exhaust" }, { "id": "el-leak-tests", "title": "How to Find an Exhaust System Leak", "url": "https://www.walkerexhaust.com/support/tech-tips/finding-exhaust-system-leaks.html", "publisher": "Walker Exhaust" }, { "id": "el-exhaust-inspection", "title": "How to Perform an Exhaust System Inspection", "url": "https://www.walkerexhaust.com/support/tech-tips/how-to-perform-exhaust-system-inspection.html", "publisher": "Walker Exhaust" }, { "id": "el-muffler", "title": "Signs of a Bad Muffler", "url": "https://www.walkerexhaust.com/support/exhaust-101/signs-of-a-bad-muffler.html", "publisher": "Walker Exhaust" }, { "id": "el-hangers", "title": "Take the Stress Out of Hanging Exhaust", "url": "https://www.walkerexhaust.com/content/dam/marketing/North-America/walker-exhaust/lv/support/sgs/preventing-stress-on-exhaust-hangers/walker-servicegram-vol1-no2-stress-on-exhaust-hangers.pdf", "publisher": "Walker Exhaust" }, { "id": "el-charcoal", "title": "Activated carbon container: function, faults and diagnosis", "url": "https://www.hella.com/techworld/au/technical/car-electronics-and-electrics/activated-charcoal-canister/", "publisher": "HELLA" }, { "id": "el-evap", "title": "What Is an EVAP System? Common Problems and Diagnostics", "url": "https://www.standardbrand.com/training-insights/training/what-is-an-evap-system-how-evaporative-emission-systems-work-common-problems-and-diagnostics/", "publisher": "Standard Motor Products" }, { "id": "el-ac-basics", "title": "DENSO: the real A/C Specialists", "url": "https://www.denso-am.eu/news/20130301_denso-the-real-ac-specialists", "publisher": "DENSO" }, { "id": "el-ac-service", "title": "Air-conditioning service: function and repairs", "url": "https://www.hella.com/techworld/au/technical/car-air-conditioning/car-air-conditioning/", "publisher": "HELLA" }, { "id": "el-compressor", "title": "How A/C compressors work", "url": "https://www.denso-am.eu/products/ac-engine-cooling/ac-compressor", "publisher": "DENSO" }, { "id": "el-condenser", "title": "How A/C condensers work", "url": "https://www.denso-am.eu/products/ac-engine-cooling/condensers", "publisher": "DENSO" }, { "id": "el-evaporator", "title": "A/C evaporators", "url": "https://www.denso-am.eu/products/ac-engine-cooling/evaporators", "publisher": "DENSO" }, { "id": "el-expansion", "title": "How expansion valves work", "url": "https://www.denso-am.eu/products/ac-engine-cooling/expansion-valves", "publisher": "DENSO" }, { "id": "el-drier", "title": "How receiver driers work", "url": "https://www.denso-am.eu/products/ac-engine-cooling/receiver-drier", "publisher": "DENSO" }, { "id": "el-blower", "title": "Cabin blower fans", "url": "https://www.denso-am.eu/products/ac-engine-cooling/cabin-blower-fans", "publisher": "DENSO" }, { "id": "el-blower-control", "title": "HVAC actuators and resistors", "url": "https://www.denso-am.eu/products/ac-engine-cooling/actuators-resistors", "publisher": "DENSO" }, { "id": "el-air-doors", "title": "HVAC Doors and Actuators", "url": "https://www.dormanproducts.com/pages/products/air-door-actuators/index.aspx", "publisher": "Dorman Products" }, { "id": "el-cabin-filter", "title": "Cabin Air Filter: how it works and when to 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{ "id": "el-window", "title": "Power Window Regulator Diagnostic Flowchart", "url": "https://m.media-amazon.com/images/I/61sn943VmHS.pdf", "publisher": "Dorman Products, manufacturer document hosted by Amazon" }, { "id": "el-wipers", "title": "Replacing windshield wipers and wiper motors", "url": "https://hella-wiperblades.com/en/article/replacing-wipers", "publisher": "HELLA" }, { "id": "el-lamps", "title": "Contemporary rear lamps: design, technology and diagnostics", "url": "https://www.hella.com/techworld/us/technical/automotive-lighting/contemporary-rear-lamps/", "publisher": "HELLA" }, { "id": "el-seat-belts", "title": "Seat Belt Safety", "url": "https://www.nhtsa.gov/vehicle-safety/seat-belts", "publisher": "NHTSA" }, { "id": "el-airbags", "title": "Air Bags: protection and replacement", "url": "https://www.nhtsa.gov/vehicle-safety/air-bags", "publisher": "NHTSA" }, { "id": "el-srs", "title": "Car airbag system: design, function and diagnosis", "url": "https://www.hella.com/techworld/en/technical/car-electronics-and-electrics/car-airbag-system/", "publisher": "HELLA" }, { "id": "el-latch", "title": "Ford door latch safety recall 19S03, owner notice", "url": "https://static.nhtsa.gov/odi/rcl/2019/RCRN-19V077-9995.pdf", "publisher": "Ford, hosted by NHTSA" }, { "id": "el-horn", "title": "Car horn circuit and installation guidance", "url": "https://www.hella.com/techworld/au/technical/car-electronics-and-electrics/car-horn-replacement/", "publisher": "HELLA" }, { "id": "el-start-chart", "title": "Starters and Alternators Diagnostic Chart", "url": "https://assets.denso-am.eu/production/attachments/Starter-Alternator-Technical-Poster-English.pdf", "publisher": "DENSO" }, { "id": "el-ac-guide", "title": "Practical tips on A/C service and compressor replacement", "url": "https://assets.denso-am.eu/production/attachments/DENSO-AC_brochure_tips-and-tricks_EN.pdf", "publisher": "DENSO" }, { "id": "el-belt-inspection", "title": "Honda Jazz Owner's Manual: Seat Belt Inspection", "url": "https://www.hondacarindia.com/ownersmanual/webom/eng/jazz/2016/details/106278046-2621", "publisher": "Honda" }, { "id": "qa-gdi-ticking", "title": "Clicking and ticking during cold start, Bulletin 07-06-04-025L", "url": "https://static.nhtsa.gov/odi/tsbs/2017/MC-10116587-9999.pdf", "publisher": "General Motors, hosted by NHTSA" }, { "id": "qa-lubrication-ticking", "title": "Engine concerns from maintenance or service conditions, Bulletin 16-NA-222", "url": "https://static.nhtsa.gov/odi/tsbs/2024/MC-11007121-0001.pdf", "publisher": "General Motors, hosted by NHTSA" }, { "id": "qa-vehicle-fire", "title": "Vehicle Fire Safety", "url": "https://www.usfa.fema.gov/prevention/vehicle-fires/", "publisher": "U.S. Fire Administration" }, { "id": "qa-disc-damage", "title": "The Brembo Guide to Brake Disc Assembly and Maintenance", "url": "https://www.bremboparts.com/zh/media/page/documents/8b6fd884-e07b-4e99-96b2-16c493862e44", "publisher": "Brembo" } ], "systems": [ { "id": "engine", "name": "Engine", "summary": "Turns combustion into rotation. Lubrication, cylinder sealing and valve timing work together. Similar symptoms can come from several parts. A red oil-pressure warning or heavy new knock calls for stopping safely and switching off.", "components": [ { "id": "engine-pistons-rings", "name": "Pistons and piston rings", "does": "Pistons turn combustion pressure into movement. Rings seal the cylinders and control oil on their walls.", "notice": "Increasing oil use, lower power or repeated plug fouling may justify checking cylinder sealing.", "hear": "There may be no distinctive sound. Mechanical wear can also cause abnormal engine noise.", "feel": "Uneven running can accompany poor cylinder sealing.", "seeSmell": "Blue exhaust smoke or falling oil level may occur, but leaks and crankcase ventilation can look similar.", "driverQuote": "I keep adding oil, but I cannot find a puddle.", "possibleCauses": [ "Ring or cylinder wear", "Dirt entering through a damaged intake", "Overheating or inadequate lubrication" ], "ifIgnored": "Oil consumption and wear may worsen; low oil can damage bearings and other moving parts.", "diagnosis": "A technician checks oil consumption, external leaks, ventilation, compression and cylinder leakage before blaming the rings.", "urgency": "soon", "relatedIds": [ "engine-pcv", "engine-oil-pump", "fuel-air-air-filter", "ignition-spark-plugs" ], "sourceIds": [ "pt-pistons", "pt-mechanical" ] }, { "id": "engine-crankshaft-bearings", "name": "Crankshaft and connecting-rod bearings", "does": "Support the rotating crankshaft and connecting rods on a protective oil film.", "notice": "New heavy mechanical noise or an oil-pressure warning needs immediate attention.", "hear": "A deep knock can accompany internal damage, but sound alone cannot identify a bearing.", "feel": "Severe damage may cause vibration or loss of smooth running.", "seeSmell": "Metal particles may be found during professional oil inspection; there may be no visible external sign.", "driverQuote": "There is a deep knocking noise that was not there yesterday.", "possibleCauses": [ "Insufficient lubrication", "Contaminated oil", "Incorrect clearances", "Overheating" ], "ifIgnored": "Bearing surfaces and the crankshaft can be destroyed, potentially seizing the engine.", "diagnosis": "Stop for a heavy new knock or oil-pressure warning. The shop checks actual oil pressure, oil debris and bearing clearances.", "urgency": "stop", "relatedIds": [ "engine-oil-pump", "engine-oil-filter", "engine-pistons-rings" ], "sourceIds": [ "pt-bearings", "pt-warning" ] }, { "id": "engine-valves", "name": "Intake and exhaust valves", "does": "Open to admit air or release exhaust, then close against their seats to seal each cylinder.", "notice": "Persistent rough running or low power can follow a valve that fails to seal.", "hear": "Uneven exhaust rhythm may accompany lost compression. A valve fault need not make a clear tick.", "feel": "A weak cylinder can make idle uneven.", "seeSmell": "There is often no visible clue; a misfire warning may accompany poor combustion.", "driverQuote": "It keeps running unevenly even after the ignition parts were checked.", "possibleCauses": [ "Burnt valve or damaged seat", "Incorrect valve clearance", "Worn guides", "Timing-related contact damage" ], "ifIgnored": "Heat leaking past a valve can worsen damage to the valve, seat and cylinder.", "diagnosis": "A technician compares cylinder compression and leakage, then checks valve clearance and mechanical timing.", "urgency": "soon", "relatedIds": [ "engine-timing-belt", "engine-timing-chain", "engine-pistons-rings" ], "sourceIds": [ "pt-valves", "pt-mechanical" ] }, { "id": "engine-oil-pump", "name": "Oil pump and pressure control", "does": "Circulates oil to lubricated engine parts. Variable pumps, where equipped, adjust delivery to engine demand.", "notice": "An oil-pressure warning while running is urgent, even when the oil level looks normal.", "hear": "Oil starvation may produce new mechanical noise; silence does not make the warning safe.", "feel": "There may be no early change in driving feel.", "seeSmell": "The oil-pressure lamp or message may appear without any puddle.", "driverQuote": "The oil warning came on, but the dipstick is not empty.", "possibleCauses": [ "Pump or pressure-control fault", "Oil loss", "Restricted supply", "Worn engine internals", "Sensor or wiring fault" ], "ifIgnored": "Inadequate oil supply can rapidly damage bearings and valve-timing parts.", "diagnosis": "Stop safely and switch off. A shop verifies actual pressure and checks oil supply and the warning circuit.", "urgency": "stop", "relatedIds": [ "engine-oil-filter", "engine-crankshaft-bearings", "engine-timing-chain" ], "sourceIds": [ "pt-oilpump", "pt-oilpressure", "pt-warning" ] }, { "id": "engine-oil-filter", "name": "Oil filter and housing seals", "does": "Traps particles in circulating oil while the housing and seals retain the oil.", "notice": "Oil loss after service or leakage around the filter needs inspection.", "hear": "The filter has no distinctive failure sound.", "feel": "Usually no direct change until lubrication is affected.", "seeSmell": "Oil wetness or drips may appear near the housing. Oil reaching hot surfaces may smell burnt.", "driverQuote": "I started seeing oil spots after the last service.", "possibleCauses": [ "Damaged or misplaced seal", "Wrong filter", "Loose or damaged housing", "Excessive pressure from a control fault" ], "ifIgnored": "Oil loss or poor filtration can increase engine wear. Stop if the oil-pressure warning appears.", "diagnosis": "A technician traces the leak, checks filter fitment and seals, and investigates abnormal oil pressure when indicated.", "urgency": "soon", "relatedIds": [ "engine-oil-pump", "engine-crankshaft-bearings", "engine-pcv" ], "sourceIds": [ "pt-filters", "pt-leaks" ] }, { "id": "engine-timing-belt", "name": "Timing belt, tensioner and idlers", "does": "Where equipped, keeps crankshaft and camshaft rotation synchronized so valves move at the right time.", "notice": "Poor running, sudden shutdown or an overdue replacement interval may point toward a timing-system inspection.", "hear": "A worn tensioner or idler may rattle. A belt can also fail without audible warning.", "feel": "Incorrect timing can cause roughness or lost power.", "seeSmell": "Most of the system is hidden. A technician may find belt damage or contamination.", "driverQuote": "The engine stopped suddenly and now will not start.", "possibleCauses": [ "Belt deterioration", "Tensioner or idler failure", "Drive-component seizure", "Incorrect installation" ], "ifIgnored": "Loss of timing can damage valves and pistons on interference engines.", "diagnosis": "A shop verifies mechanical timing and the complete belt drive. After sudden failure, avoid repeated starting attempts.", "urgency": "soon", "relatedIds": [ "engine-valves", "cooling-water-pump", "ignition-cam-sensor" ], "sourceIds": [ "pt-belt" ] }, { "id": "engine-timing-chain", "name": "Timing chain, guides and tensioner", "does": "Where equipped, synchronizes valve timing. Guides control the chain path; a tensioner manages slack.", "notice": "New startup rattling, timing-related faults or rough running warrant prompt investigation.", "hear": "Rattle, scraping or chain slap can occur, especially at startup or during load changes.", "feel": "Timing drift may reduce smoothness and power.", "seeSmell": "There is usually no external clue; broken guide fragments may be found in the oil system.", "driverQuote": "It rattles briefly when I first start it.", "possibleCauses": [ "Chain and sprocket wear", "Failed guide or tensioner", "Poor oil supply", "Incorrect oil or contamination" ], "ifIgnored": "The chain can jump timing and cause internal engine damage.", "diagnosis": "A technician checks oil condition and pressure, cam/crank correlation and the chain drive. Persistent loud rattling needs immediate assessment.", "urgency": "soon", "relatedIds": [ "engine-oil-pump", "engine-valves", "ignition-crank-sensor", "ignition-cam-sensor" ], "sourceIds": [ "pt-chain" ] }, { "id": "engine-pcv", "name": "Crankcase ventilation valve and separator", "does": "Routes blow-by gases back to the intake while controlling crankcase pressure and separating oil mist.", "notice": "Oil leaks, oil consumption or unstable idle can involve the ventilation system.", "hear": "A leak may be audible, but there is no single reliable PCV failure sound.", "feel": "An unintended air leak can make idle uneven.", "seeSmell": "Oil may collect around seals or in intake plumbing; sludge can restrict ventilation.", "driverQuote": "It has started leaking oil and idling unevenly.", "possibleCauses": [ "Blocked valve or breather hose", "Failed regulating diaphragm", "Restricted oil separator", "Excessive engine blow-by" ], "ifIgnored": "Pressure can force oil through seals, while trapped vapors promote sludge and oil deterioration.", "diagnosis": "A shop tests crankcase pressure and ventilation flow, checks hoses and separates PCV faults from internal engine wear.", "urgency": "soon", "relatedIds": [ "engine-pistons-rings", "fuel-air-intake-manifold", "engine-oil-filter" ], "sourceIds": [ "pt-pcv", "pt-mechanical" ] } ] }, { "id": "transmission", "name": "Transmission", "summary": "Transfers engine power through suitable ratios. Manual, conventional automatic, CVT and dual-clutch layouts differ. Entries apply only where equipped. Shift symptoms also depend on fluid, engine operation and controls.", "components": [ { "id": "transmission-torque-converter", "name": "Torque converter and lockup clutch", "does": "Where equipped, couples the engine to the gearbox through fluid. A lockup clutch reduces cruising slip.", "notice": "Cruising shudder, unwanted slip or stalling as the car stops can involve lockup control.", "hear": "There may be no distinctive sound.", "feel": "A vibration may appear during light-throttle cruising.", "seeSmell": "A warning lamp may appear; visible leaks are not required.", "driverQuote": "It feels like driving over tiny bumps at a steady speed.", "possibleCauses": [ "Lockup friction wear", "Incorrect fluid", "Low apply pressure", "Restricted cooling flow", "Engine misfire mimicking shudder" ], "ifIgnored": "Excess heat can damage the converter and transmission.", "diagnosis": "A specialist compares lockup command, slip speed, fluid specification, pressures and cooler flow.", "urgency": "soon", "relatedIds": [ "transmission-valve-body", "transmission-pump", "transmission-cooler", "ignition-spark-plugs" ], "sourceIds": [ "pt-lockup" ] }, { "id": "transmission-pump", "name": "Transmission oil pump", "does": "Where equipped, supplies hydraulic flow for clutch application, converter operation, cooling and lubrication.", "notice": "Delayed engagement, slipping or overheating can follow inadequate flow.", "hear": "Pump or bushing wear may produce abnormal noise.", "feel": "Drive may engage slowly or inconsistently.", "seeSmell": "Fluid leaks or an overheating warning may accompany the problem.", "driverQuote": "It hesitates before moving when I select Drive.", "possibleCauses": [ "Pump wear", "Internal leakage", "Pressure-regulator trouble", "Restricted supply" ], "ifIgnored": "Poor lubrication and clutch pressure can cause wider transmission damage.", "diagnosis": "A specialist checks fluid supply, line pressure, cooler flow and internal leakage together.", "urgency": "soon", "relatedIds": [ "transmission-valve-body", "transmission-clutch-packs", "transmission-torque-converter", "transmission-cooler" ], "sourceIds": [ "pt-transpump" ] }, { "id": "transmission-valve-body", "name": "Valve body and hydraulic passages", "does": "Where equipped, routes transmission fluid to the clutches and converter control circuits.", "notice": "Harsh, delayed or flaring shifts can result from incorrect hydraulic pressure.", "hear": "A shift clunk may occur, but does not identify the valve body.", "feel": "Gear changes may bump, slip or briefly bind.", "seeSmell": "A transmission warning may appear with no external leak.", "driverQuote": "Some shifts hit hard and others feel slow.", "possibleCauses": [ "Worn valve bores", "Leaking seals or end plugs", "Sticking valves", "Pressure-control faults" ], "ifIgnored": "Repeated pressure loss or harsh application can overheat or wear clutches.", "diagnosis": "The shop compares commanded and actual operation, then tests relevant hydraulic circuits and valve-body leakage.", "urgency": "soon", "relatedIds": [ "transmission-solenoids", "transmission-pump", "transmission-clutch-packs" ], "sourceIds": [ "pt-valvebody" ] }, { "id": "transmission-solenoids", "name": "Shift and pressure-control solenoids", "does": "Where equipped, convert control-module commands into hydraulic changes for shifting or converter lockup.", "notice": "Wrong-gear starts, harsh shifts or lockup faults can involve these circuits.", "hear": "No distinctive sound reliably identifies a failed solenoid.", "feel": "Shifts may be abrupt or the gearbox may stay in a fallback gear.", "seeSmell": "A transmission or engine warning may appear.", "driverQuote": "It suddenly shifts hard and seems stuck in one gear.", "possibleCauses": [ "Solenoid fault", "Wiring or connector trouble", "Contamination", "Hydraulic faults that imitate electrical trouble" ], "ifIgnored": "Incorrect clutch pressure can increase heat and wear.", "diagnosis": "A specialist checks commands, electrical supply and hydraulic response before replacing a solenoid.", "urgency": "soon", "relatedIds": [ "transmission-valve-body", "transmission-speed-sensors", "transmission-torque-converter" ], "sourceIds": [ "pt-transdiagnosis" ] }, { "id": "transmission-clutch-packs", "name": "Automatic transmission clutch packs", "does": "Where equipped, grip internal transmission members to establish the commanded gear ratio.", "notice": "Engine speed rising during a shift without matching acceleration can indicate clutch slip.", "hear": "The engine may flare in pitch; the clutch itself has no unique sound.", "feel": "Acceleration may pause or a gear may fail to hold.", "seeSmell": "Overheated fluid or friction debris may be found during service.", "driverQuote": "The revs rise between gears but the car does not speed up.", "possibleCauses": [ "Worn friction plates", "Low apply pressure", "Leaking internal seals", "Control faults" ], "ifIgnored": "Slip generates heat that can burn friction material and spread debris.", "diagnosis": "The shop checks gear-ratio data, pressures and apply-circuit leakage, rather than assuming worn plates alone.", "urgency": "soon", "relatedIds": [ "transmission-pump", "transmission-valve-body", "transmission-solenoids" ], "sourceIds": [ "pt-clutchpacks" ] }, { "id": "transmission-speed-sensors", "name": "Transmission input and output speed sensors", "does": "Where equipped, report shaft speed so the controller can select gears and regulate shifts.", "notice": "A transmission warning and fallback shifting can follow an implausible speed signal.", "hear": "No distinctive sound.", "feel": "Shift behavior may change or acceleration may be limited.", "seeSmell": "Usually a warning lamp rather than a visible mechanical symptom.", "driverQuote": "A warning came on and the gearbox stopped shifting normally.", "possibleCauses": [ "Sensor circuit fault", "Damaged wiring", "Metal contamination", "Damaged trigger wheel" ], "ifIgnored": "Unreliable signals can keep the gearbox in restricted operation.", "diagnosis": "A technician checks fault data, signal waveforms, wiring and the trigger wheel against vehicle specifications.", "urgency": "soon", "relatedIds": [ "transmission-solenoids", "transmission-valve-body" ], "sourceIds": [ "pt-transspeed" ] }, { "id": "transmission-cooler", "name": "Transmission cooler and lines", "does": "Where equipped, remove heat from transmission fluid through airflow or the engine coolant circuit.", "notice": "Temperature warnings or shifting that worsens when hot merit inspection.", "hear": "No distinctive cooler failure sound.", "feel": "Overheating may change shift quality or limit drive.", "seeSmell": "Fluid may leak around lines or the cooler; fluid color alone does not identify the leak.", "driverQuote": "It shifts worse after a long climb.", "possibleCauses": [ "Restricted cooler flow", "Corrosion or impact damage", "Leaking connections", "Poor heat transfer" ], "ifIgnored": "Fluid loss and heat can damage clutches, seals and lubricated parts.", "diagnosis": "The shop checks leak origin, fluid temperature and cooler flow, including the connected engine cooling system where relevant.", "urgency": "soon", "relatedIds": [ "transmission-pump", "transmission-torque-converter", "cooling-radiator" ], "sourceIds": [ "pt-transcooler" ] }, { "id": "transmission-manual-clutch", "name": "Manual clutch disc and pressure plate", "does": "Where equipped, connect engine rotation to the gearbox and separate them for shifts.", "notice": "Revs increasing without proportional road speed can indicate clutch slip.", "hear": "Engine speed rises; there may be no separate clutch noise.", "feel": "The clutch may slip most under load.", "seeSmell": "Prolonged slipping may produce a hot friction smell.", "driverQuote": "The engine revs on hills but the car barely picks up speed.", "possibleCauses": [ "Worn friction lining", "Oil contamination", "Weak clamp force", "Release system holding the clutch partly open" ], "ifIgnored": "Continued slipping overheats the clutch and can damage adjacent friction surfaces.", "diagnosis": "A shop checks release operation, oil contamination and clutch condition. Intentional high-load slip tests are unnecessary for the driver.", "urgency": "soon", "relatedIds": [ "transmission-clutch-release", "transmission-flywheel" ], "sourceIds": [ "pt-clutch" ] }, { "id": "transmission-clutch-release", "name": "Clutch release bearing and actuation", "does": "Where equipped, translates pedal input through hydraulics or a cable to release the clutch.", "notice": "Difficulty selecting gears can mean the clutch is not fully separating.", "hear": "Release-system wear may cause noise when the pedal is operated.", "feel": "Pedal movement or disengagement may become inconsistent.", "seeSmell": "A hydraulic leak may be present; not every release fault leaks.", "driverQuote": "The gears are hard to select with the clutch pedal down.", "possibleCauses": [ "Slave cylinder or cable fault", "Worn release bearing or pivot", "Incorrect adjustment", "Clutch disc or pilot-bearing trouble" ], "ifIgnored": "Gear selection can become unreliable and clutch components may suffer further damage.", "diagnosis": "The shop checks release travel, hydraulics or cable operation, bearings and clutch movement.", "urgency": "soon", "relatedIds": [ "transmission-manual-clutch", "transmission-flywheel" ], "sourceIds": [ "pt-release" ] }, { "id": "transmission-flywheel", "name": "Dual-mass flywheel", "does": "Where equipped, dampens engine torsional vibration before it reaches the gearbox.", "notice": "Start, shutdown or low-speed driveline rattles call for checking the flywheel and surrounding systems.", "hear": "Rattling or chattering may occur around the clutch housing.", "feel": "Shudder or bucking can accompany uneven engine operation.", "seeSmell": "There is usually no external visual clue.", "driverQuote": "It chatters when starting and sometimes bucks at low revs.", "possibleCauses": [ "Flywheel wear", "Low cranking speed", "Poor electrical connections", "Engine misfire", "Unsuitable low-speed loading" ], "ifIgnored": "Excess vibration can shorten flywheel life and stress the clutch area.", "diagnosis": "A technician checks starting speed, electrical supply and engine smoothness before condemning the flywheel.", "urgency": "soon", "relatedIds": [ "transmission-manual-clutch", "transmission-clutch-release", "ignition-ignition-coils" ], "sourceIds": [ "pt-dmf" ] } ] }, { "id": "fuel-air", "name": "Fuel and air", "summary": "Meters clean air and fuel for combustion. Low pressure, contaminated fuel, air leaks and misleading sensor signals can produce similar complaints. A strong raw-fuel smell or visible fuel leak means stop safely and arrange assistance.", "components": [ { "id": "fuel-air-fuel-pump", "name": "Tank fuel pump and supply circuit", "does": "Moves fuel from the tank toward the engine at the pressure and flow the fuel system needs.", "notice": "Poor starting, stalling or weak acceleration can occur when fuel delivery is insufficient.", "hear": "Pump sound alone cannot establish whether pressure and flow are adequate.", "feel": "The engine may hesitate or lose power under demand.", "seeSmell": "Often no visible clue. Raw fuel odor or wet fuel requires stopping.", "driverQuote": "It starts slowly and runs out of power when I accelerate.", "possibleCauses": [ "Pump wear", "Low supply voltage or poor ground", "Restricted fuel supply", "Fuel contamination" ], "ifIgnored": "Unreliable delivery can lead to stalling or a no-start.", "diagnosis": "A professional compares fuel pressure and volume with specifications and checks voltage drop before condemning the pump.", "urgency": "soon", "relatedIds": [ "fuel-air-fuel-filter", "fuel-air-high-pressure-pump", "fuel-air-injectors" ], "sourceIds": [ "pt-fuelpressure", "pt-fuelvoltage", "pt-highpump", "pt-fuelleaksafety" ] }, { "id": "fuel-air-high-pressure-pump", "name": "Gasoline high-pressure pump", "does": "On direct-injection engines where equipped, raises supply pressure before fuel reaches the rail and injectors.", "notice": "Poor starting, reduced power or fuel-pressure faults can involve the high-pressure circuit.", "hear": "A mechanical pump may normally tick; sound alone does not establish failure.", "feel": "Acceleration may hesitate or be restricted.", "seeSmell": "A warning lamp may appear. Any fuel leak needs immediate attention.", "driverQuote": "It loses power and the shop found a fuel-pressure fault.", "possibleCauses": [ "Insufficient low-pressure feed", "Pump or drive wear", "Pressure-control fault", "Incorrect sensor signal" ], "ifIgnored": "Starting and performance problems can worsen.", "diagnosis": "A specialist compares commanded and actual pressures, checks supply first and inspects pump control and mechanical drive.", "urgency": "soon", "relatedIds": [ "fuel-air-fuel-pump", "fuel-air-injectors", "engine-valves", "engine-oil-pump" ], "sourceIds": [ "pt-highpump", "pt-fuelleaksafety", "qa-gdi-ticking", "qa-lubrication-ticking" ] }, { "id": "fuel-air-injectors", "name": "Fuel injectors", "does": "Meter and spray the fuel quantity requested for each cylinder.", "notice": "Hard starting, uneven idle, higher fuel use or loss of power may involve an injector.", "hear": "Uneven combustion may sound like sputtering; normal injector ticking is not proof of failure.", "feel": "A cylinder receiving the wrong amount can make the engine shake.", "seeSmell": "Poor combustion may affect exhaust emissions. Visible fuel or a strong fuel smell is urgent.", "driverQuote": "It shakes at idle and uses more fuel than before.", "possibleCauses": [ "Deposits or contaminated fuel", "Leaking injector needle", "Electrical coil or wiring fault", "Incorrect supply pressure" ], "ifIgnored": "Persistent fueling errors may harm the engine or catalytic converter.", "diagnosis": "A technician compares cylinder contribution, injector signals, pressure and leakage, using suitable equipment for the injection type.", "urgency": "soon", "relatedIds": [ "fuel-air-fuel-filter", "fuel-air-high-pressure-pump", "ignition-spark-plugs" ], "sourceIds": [ "pt-injector", "pt-leaks", "pt-fuelleaksafety" ] }, { "id": "fuel-air-fuel-filter", "name": "Fuel filter and strainer", "does": "Keeps contamination out of the fuel delivery system. Location and serviceability vary by vehicle.", "notice": "A substantial restriction may cause weak acceleration or prevent starting.", "hear": "The filter has no distinctive failure sound.", "feel": "The engine may feel especially sluggish when fuel demand is high.", "seeSmell": "Usually no visible sign. Fuel wetness around a serviceable filter indicates a separate leak concern.", "driverQuote": "It feels weak when I try to pass another car.", "possibleCauses": [ "Contaminated fuel", "Blocked filter media", "Incorrect filter", "Restricted tank strainer" ], "ifIgnored": "Fuel starvation may worsen and contamination can affect downstream parts.", "diagnosis": "A shop checks pressure and flow, identifies the restriction and follows the vehicle-specific service schedule.", "urgency": "soon", "relatedIds": [ "fuel-air-fuel-pump", "fuel-air-injectors" ], "sourceIds": [ "pt-fuelfilter" ] }, { "id": "fuel-air-maf-sensor", "name": "Mass airflow sensor", "does": "Where equipped, measures entering air so the engine controller can calculate fuel delivery.", "notice": "Rough idle, stalling, changing idle speed or a warning lamp may accompany an inaccurate signal.", "hear": "No distinctive sensor sound.", "feel": "Vibration at idle or hesitant acceleration can occur.", "seeSmell": "Usually only a warning lamp; contamination may be found during inspection.", "driverQuote": "The idle keeps changing even though my foot is off the pedal.", "possibleCauses": [ "Contaminated measuring element", "Damaged connector or wiring", "Sensor drift", "Intake leakage mimicking a sensor problem" ], "ifIgnored": "Poor mixture control can increase emissions and worsen driveability.", "diagnosis": "A technician checks airflow data, supply and signal integrity while also inspecting intake leaks and ignition or injector faults.", "urgency": "soon", "relatedIds": [ "fuel-air-air-filter", "fuel-air-intake-manifold", "fuel-air-injectors" ], "sourceIds": [ "pt-maf" ] }, { "id": "fuel-air-map-sensor", "name": "Manifold pressure sensor", "does": "Where equipped, reports intake pressure for load calculation, fueling and ignition timing.", "notice": "Poor economy, hesitation, stalling or a warning lamp can accompany an incorrect pressure reading.", "hear": "No distinctive sensor sound; abnormal combustion may produce pinging or popping.", "feel": "The engine may surge or hesitate.", "seeSmell": "An overly rich mixture may create a fuel smell, but leaks must first be excluded.", "driverQuote": "It hesitates and smells rich when idling.", "possibleCauses": [ "Sensor contamination", "Blocked or leaking sensing hose", "Damaged wiring", "Real intake-pressure problems" ], "ifIgnored": "Incorrect mixture control may worsen emissions and engine operation.", "diagnosis": "A shop compares pressure readings with expected conditions and checks wiring and hoses; a fault code alone does not prove sensor failure.", "urgency": "soon", "relatedIds": [ "fuel-air-intake-manifold", "ignition-throttle-body", "ignition-knock-sensor" ], "sourceIds": [ "pt-map" ] }, { "id": "fuel-air-air-filter", "name": "Engine air filter and airbox", "does": "Supplies filtered air while keeping abrasive dirt away from the airflow sensor and engine.", "notice": "Severe restriction can reduce power; a damaged filter may allow harmful dirt through without an obvious driving symptom.", "hear": "Often no unusual sound, even with reduced performance.", "feel": "Substantial restriction may feel like weak acceleration.", "seeSmell": "Inspection may reveal heavy contamination, torn media or poor sealing.", "driverQuote": "It feels short of power, but the engine sounds normal.", "possibleCauses": [ "Clogged filter", "Damaged media", "Incorrect fitment", "Airbox sealing problem" ], "ifIgnored": "Dirt bypass can damage the sensor and wear cylinder surfaces.", "diagnosis": "A technician inspects the filter, housing and intake path, checking restriction and fit rather than judging by color alone.", "urgency": "inspect", "relatedIds": [ "fuel-air-maf-sensor", "engine-pistons-rings", "fuel-air-intake-manifold" ], "sourceIds": [ "pt-airfilter", "pt-filters" ] }, { "id": "fuel-air-intake-manifold", "name": "Intake manifold, gaskets and intake plumbing", "does": "Distributes incoming air to the cylinders. Seals keep unwanted air out; some designs also carry coolant.", "notice": "Rough running, lean-mixture faults or coolant loss on relevant designs can involve intake leaks.", "hear": "Some air leaks hiss, but many are quiet.", "feel": "An air leak may cause uneven idle or hesitation.", "seeSmell": "Coolant residue can occur where coolant passages are present. A dry manifold can still leak air.", "driverQuote": "It idles badly and the warning light keeps returning.", "possibleCauses": [ "Aged gasket", "Cracked manifold or hose", "Loose connection", "Related crankcase-ventilation fault" ], "ifIgnored": "Mixture errors may continue; coolant loss can lead to overheating.", "diagnosis": "A shop checks fuel-trim and pressure data, performs controlled intake-leak testing and pressure-tests coolant passages where applicable.", "urgency": "soon", "relatedIds": [ "engine-pcv", "fuel-air-map-sensor", "ignition-throttle-body", "cooling-head-gasket" ], "sourceIds": [ "pt-manifold", "pt-leaks", "pt-mechanical" ] } ] }, { "id": "cooling", "name": "Cooling", "summary": "Moves engine heat into the surrounding air and supplies cabin heat. Temperature, circulation, airflow and pressure all matter. Stop for overheating, steam or rapid coolant loss. Never open a hot cooling-system cap.", "components": [ { "id": "cooling-water-pump", "name": "Water pump", "does": "Circulates coolant through the engine, radiator and heater circuit. Drive type varies by vehicle.", "notice": "Coolant loss or rising temperature can involve pump leakage or poor circulation.", "hear": "Worn bearings may make abnormal noise near the pump drive.", "feel": "Often no early change in driving feel.", "seeSmell": "Coolant tracks may appear at the pump or its mounting surface.", "driverQuote": "There is coolant near the front of the engine and it is running hot.", "possibleCauses": [ "Seal or bearing wear", "Corroded or loose impeller", "Contaminated coolant", "Drive-system fault" ], "ifIgnored": "Overheating can damage the engine; leakage may also affect nearby belt components.", "diagnosis": "A technician checks leakage, circulation, drive condition and the rest of the cooling system.", "urgency": "soon", "relatedIds": [ "engine-timing-belt", "cooling-thermostat", "cooling-radiator", "cooling-head-gasket" ], "sourceIds": [ "pt-waterpump" ] }, { "id": "cooling-radiator", "name": "Radiator", "does": "Transfers heat from coolant into air passing through its tubes and fins.", "notice": "Repeated overheating or coolant loss may involve restricted flow, poor airflow or leakage.", "hear": "Usually no distinctive failure sound.", "feel": "The engine may lose performance if it overheats.", "seeSmell": "Wet seams, dried coolant or damaged and obstructed fins may be visible.", "driverQuote": "The temperature climbs even though there is coolant in the tank.", "possibleCauses": [ "Internal blockage", "External airflow obstruction", "Corrosion or impact damage", "Leaking tank or seam" ], "ifIgnored": "Lost cooling capacity or coolant can lead to severe overheating.", "diagnosis": "A shop pressure-tests for leaks and checks temperature distribution, coolant flow and airflow.", "urgency": "soon", "relatedIds": [ "cooling-fans", "cooling-hoses", "cooling-water-pump", "transmission-cooler" ], "sourceIds": [ "pt-radiator", "pt-coolingchecks" ] }, { "id": "cooling-thermostat", "name": "Thermostat and housing", "does": "Regulates coolant routing so the engine warms up and stays within its intended temperature range.", "notice": "Slow warm-up suggests a different fault pattern from rapid overheating.", "hear": "No distinctive thermostat sound.", "feel": "Cabin heat may stay weak when the thermostat remains open.", "seeSmell": "A temperature warning or coolant leakage around the housing may appear.", "driverQuote": "The heater stays lukewarm and the temperature gauge barely rises.", "possibleCauses": [ "Thermostat stuck open or closed", "Deposits or corrosion", "Housing seal leak", "Electrical heating fault where equipped" ], "ifIgnored": "Running too cold wastes fuel and increases wear; blocked circulation can overheat the engine.", "diagnosis": "A technician checks warm-up behavior, temperatures and any electronic thermostat circuit.", "urgency": "soon", "relatedIds": [ "cooling-temperature-sensor", "cooling-water-pump", "cooling-heater-core" ], "sourceIds": [ "pt-thermostat" ] }, { "id": "cooling-fans", "name": "Radiator fan and motor", "does": "Moves air through the radiator when natural airflow is insufficient, especially at low road speed.", "notice": "Overheating while stationary may involve missing fan airflow.", "hear": "A worn motor or damaged blade may grind, squeal or rattle.", "feel": "Usually no direct change before temperature rises.", "seeSmell": "Damaged blades or a shroud may be visible during a safe, switched-off inspection.", "driverQuote": "It gets hot in traffic but seems better once moving.", "possibleCauses": [ "Failed fan motor", "Damaged blades", "Power-supply fault", "Missing control command" ], "ifIgnored": "Inadequate airflow can allow overheating and engine damage.", "diagnosis": "A technician checks commanded fan operation, power, ground, current draw and mechanical condition. Fans can start unexpectedly.", "urgency": "soon", "relatedIds": [ "cooling-fan-control", "cooling-radiator", "cooling-temperature-sensor" ], "sourceIds": [ "pt-fan" ] }, { "id": "cooling-fan-control", "name": "Fan relay, module and temperature control", "does": "Where equipped, switches or regulates electric fan operation in response to cooling demand.", "notice": "A fan that does not run when needed, or runs continuously, may have a control issue.", "hear": "The fan may stay unusually loud or silent when cooling is needed.", "feel": "Usually no direct driving sensation.", "seeSmell": "Temperature warnings may appear without a coolant leak.", "driverQuote": "The fan runs hard all the time, even when the engine seems cold.", "possibleCauses": [ "Relay or control-module fault", "Blown fuse or wiring problem", "Implausible temperature signal", "Fan motor fault" ], "ifIgnored": "Incorrect fan operation can cause overheating or persistent unnecessary fan operation.", "diagnosis": "A shop compares temperature readings and fan commands, then tests power delivery and motor response.", "urgency": "soon", "relatedIds": [ "cooling-fans", "cooling-temperature-sensor", "cooling-radiator" ], "sourceIds": [ "pt-coolingchecks", "pt-fan" ] }, { "id": "cooling-hoses", "name": "Coolant hoses and connections", "does": "Carry coolant between the engine, radiator, tank and heater.", "notice": "Coolant loss or restricted circulation may come from a hose or connection.", "hear": "A pressurized leak may hiss; many leaks are silent.", "feel": "Loss of cabin heat may accompany circulation problems.", "seeSmell": "Cracking, rubbing, swelling, wet joints or dried coolant may be found.", "driverQuote": "There is coolant under the car and the level keeps dropping.", "possibleCauses": [ "Age and internal degradation", "Heat or oil damage", "Abrasion", "Loose connection", "Kinked hose" ], "ifIgnored": "A small leak can become rapid coolant loss and overheating.", "diagnosis": "A technician checks the cold system for hose damage and pressure-tests it, including clamps and nearby contact points.", "urgency": "soon", "relatedIds": [ "cooling-radiator", "cooling-water-pump", "cooling-expansion-tank", "cooling-heater-core" ], "sourceIds": [ "pt-hoses" ] }, { "id": "cooling-expansion-tank", "name": "Expansion tank and pressure cap", "does": "Accommodates coolant expansion. A pressurized tank or radiator cap maintains the specified system pressure, depending on design.", "notice": "Repeated coolant loss, overflow or collapsed hoses can involve the tank or cap.", "hear": "Hissing or gurgling is not specific enough to identify the cause.", "feel": "Usually no direct change until cooling is affected.", "seeSmell": "Tank cracks, residue around the cap or an abnormal coolant level may appear.", "driverQuote": "The tank keeps losing coolant but I cannot see a large leak.", "possibleCauses": [ "Cracked tank", "Damaged cap seal or valve", "Incorrect cap rating", "Excess pressure originating elsewhere" ], "ifIgnored": "Pressure loss or coolant loss can impair cooling and damage other parts.", "diagnosis": "A shop tests the tank, cap and system pressure, checking for underlying overheating or combustion leakage.", "urgency": "soon", "relatedIds": [ "cooling-hoses", "cooling-head-gasket", "cooling-radiator" ], "sourceIds": [ "pt-tank", "pt-cap" ] }, { "id": "cooling-temperature-sensor", "name": "Coolant temperature sensor", "does": "Reports coolant temperature for engine management and, depending on design, fan control and dashboard indication.", "notice": "Poor starting, higher idle or implausible temperature readings may involve the sensor circuit.", "hear": "No distinctive sound.", "feel": "Idle or starting behavior may change.", "seeSmell": "A warning or unusual gauge reading may appear without real overheating, but must be verified.", "driverQuote": "The temperature reading suddenly jumps and the idle is higher.", "possibleCauses": [ "Sensor fault", "Corroded connector", "Wiring break or short", "Actual cooling-system problem" ], "ifIgnored": "Incorrect temperature information can disrupt fueling or cooling control.", "diagnosis": "A technician compares sensor data with actual temperature and checks the circuit. A cold-running code can also indicate a thermostat fault.", "urgency": "soon", "relatedIds": [ "cooling-fan-control", "cooling-thermostat", "fuel-air-injectors" ], "sourceIds": [ "pt-coolantsensor" ] }, { "id": "cooling-heater-core", "name": "Heater core", "does": "Passes engine heat into cabin air through a small coolant-filled heat exchanger.", "notice": "Weak cabin heat with a warm engine may involve restricted coolant flow through the core.", "hear": "No distinctive core failure sound.", "feel": "Air from the vents may stay cool despite a heat request.", "seeSmell": "A leak can cause coolant loss; reduced heat can impair windshield clearing.", "driverQuote": "The blower works, but the air never gets properly warm.", "possibleCauses": [ "Restricted core", "Coolant leak", "Air or low coolant in the circuit", "Heater valve or air-door fault" ], "ifIgnored": "Heating and demisting remain impaired; coolant loss can affect engine cooling.", "diagnosis": "A shop compares inlet and outlet temperatures, checks flow and leaks, and verifies heater valve and air-door operation.", "urgency": "soon", "relatedIds": [ "cooling-hoses", "cooling-water-pump", "cooling-thermostat", "hvac-blend-door", "hvac-blower" ], "sourceIds": [ "pt-heater", "pt-coolingchecks", "pt-leaks", "el-air-doors", "el-blower-control" ] }, { "id": "cooling-head-gasket", "name": "Head gasket and cylinder-head sealing", "does": "Seals combustion pressure and separates oil and coolant passages between the cylinder head and block.", "notice": "Unexplained coolant loss, repeated overheating or rough running can involve a sealing failure.", "hear": "Uneven combustion may be audible; no sound confirms a head-gasket fault.", "feel": "Coolant entering a cylinder may cause a misfire.", "seeSmell": "Persistent white exhaust after warm-up, coolant overflow or contaminated oil warrant testing. Condensation alone is not proof.", "driverQuote": "It keeps losing coolant and now runs rough when started.", "possibleCauses": [ "Head-gasket leakage", "Cracked or distorted cylinder head", "Prior overheating" ], "ifIgnored": "Overheating and contamination can damage engine internals, oxygen sensors and the catalytic converter.", "diagnosis": "A shop checks external leaks, cooling-system pressure and cylinder sealing. Stop if overheating or severe misfire occurs.", "urgency": "soon", "relatedIds": [ "engine-pistons-rings", "engine-valves", "cooling-expansion-tank", "ignition-spark-plugs" ], "sourceIds": [ "pt-headgasket", "pt-headcrack" ] } ] }, { "id": "ignition", "name": "Ignition and engine management", "summary": "Spark components ignite the mixture. Timing and throttle sensors help the engine computer decide when to fire and how much air to admit. Fuel, compression and wiring problems can produce the same symptoms. Ignition testing involves dangerous voltage and belongs with a trained technician.", "components": [ { "id": "ignition-spark-plugs", "name": "Spark plugs", "does": "Create the spark that ignites compressed air and fuel inside each cylinder.", "notice": "Hard starting, misfire or higher fuel use may develop.", "hear": "Uneven exhaust beats may accompany a misfire; plugs have no unique sound.", "feel": "Shaking at idle or hesitation under load.", "seeSmell": "A warning light may appear. A technician may find worn electrodes, oil deposits or cracked insulation.", "driverQuote": "It shakes at lights and skips when I accelerate.", "possibleCauses": [ "Electrode wear", "Fuel or oil fouling", "Wrong specification or installation damage", "A fuel or compression fault that fouls an otherwise sound plug" ], "ifIgnored": "Misfiring can damage the catalyst. A widening plug gap also raises demand on the coil.", "diagnosis": "Check misfire data and plug condition against the exact engine specification; investigate why deposits formed.", "urgency": "soon", "relatedIds": [ "ignition-ignition-coils", "ignition-leads", "fuel-air-injectors", "engine-pistons-rings" ], "sourceIds": [ "pt-plugs", "pt-plugwear", "pt-misfire" ] }, { "id": "ignition-ignition-coils", "name": "Ignition coils", "does": "Convert low electrical voltage into the high-voltage pulse needed by the spark plugs.", "notice": "Misfire, reduced power, a warning light or failure to start.", "hear": "Uneven engine firing, but no sound proves a coil fault.", "feel": "Jerking under load or a rough idle.", "seeSmell": "Cracks, oil or moisture around a coil may be found during inspection.", "driverQuote": "It starts, but feels like one cylinder is missing.", "possibleCauses": [ "Internal winding or insulation damage", "Oil or water contamination", "Poor power supply or corroded connections", "Plug or mechanical faults that resemble coil failure" ], "ifIgnored": "Continuing to misfire can overheat the catalytic converter and leave the car unable to run.", "diagnosis": "A technician checks supply, control signals and ignition waveforms alongside fuel delivery and compression.", "urgency": "soon", "relatedIds": [ "ignition-spark-plugs", "ignition-leads", "ignition-crank-sensor", "engine-valves" ], "sourceIds": [ "pt-coilcheck", "pt-misfire" ] }, { "id": "ignition-leads", "name": "Spark plug leads and boots", "does": "Carry and insulate high voltage between remote coils and plugs, where equipped; many engines instead place coils directly on plugs.", "notice": "An interrupted or leaking spark path can resemble a failing coil.", "hear": "No dependable distinctive sound; engine firing may become uneven.", "feel": "Intermittent hesitation or shaking.", "seeSmell": "Damaged insulation or corroded connections may be visible during a safe, engine-off inspection.", "driverQuote": "The engine misses sometimes, but the cause is not obvious.", "possibleCauses": [ "Damaged insulation", "Loose or corroded connections", "Excessive cable resistance", "Incorrect lead specification" ], "ifIgnored": "An unresolved misfire can worsen drivability and harm the catalyst.", "diagnosis": "Have a technician inspect routing, connections and insulation, then evaluate resistance and ignition behavior using the vehicle-specific procedure. Never handle live leads.", "urgency": "soon", "relatedIds": [ "ignition-ignition-coils", "ignition-spark-plugs" ], "sourceIds": [ "pt-coils", "pt-wire", "pt-coilcheck", "pt-misfire" ] }, { "id": "ignition-crank-sensor", "name": "Crankshaft position sensor", "does": "Reports crankshaft speed and position so the computer can time ignition and fuel injection.", "notice": "Intermittent stalling, hard starting or a no-start condition.", "hear": "The starter may turn normally without the engine catching.", "feel": "Sudden loss of engine power if the signal disappears.", "seeSmell": "A warning light or stored code may be the only visible clue.", "driverQuote": "It cranks normally, but sometimes will not start.", "possibleCauses": [ "Internal sensor fault", "Broken wiring or poor connector contact", "Damaged signal wheel", "Metal contamination at the sensor" ], "ifIgnored": "Intermittent failures may become a persistent no-start or repeat stall. Stop driving if it repeatedly stalls.", "diagnosis": "Check fault records, wiring and the crank signal with appropriate equipment; Hall and inductive sensors need different tests.", "urgency": "soon", "relatedIds": [ "ignition-cam-sensor", "ignition-ignition-coils", "fuel-air-injectors", "engine-crankshaft-bearings" ], "sourceIds": [ "pt-crank" ] }, { "id": "ignition-cam-sensor", "name": "Camshaft position sensor", "does": "Identifies engine-cycle position alongside the crank sensor so injection and ignition can be coordinated.", "notice": "Longer cranking, a warning light or reduced-power operation may occur.", "hear": "Usually no distinctive sound from the sensor itself.", "feel": "Sluggish response if the computer uses a fallback mode.", "seeSmell": "A warning lamp may appear without visible damage.", "driverQuote": "It takes longer to start and now the engine light is on.", "possibleCauses": [ "Sensor electronics fault", "Wiring or connector damage", "Damaged target wheel", "Mechanical timing trouble that makes the signals disagree" ], "ifIgnored": "Starting and performance may worsen; a timing-related code should not be dismissed as only a sensor.", "diagnosis": "Compare cam and crank signals, supply and wiring. Verify mechanical timing when signal correlation is wrong.", "urgency": "soon", "relatedIds": [ "ignition-crank-sensor", "engine-timing-belt", "engine-timing-chain", "fuel-air-injectors" ], "sourceIds": [ "pt-cam", "pt-chain" ] }, { "id": "ignition-knock-sensor", "name": "Knock sensor", "does": "Detects engine-block vibration associated with abnormal combustion so the computer can adjust ignition timing.", "notice": "A warning light, reduced performance or increased fuel use may occur.", "hear": "A sensor fault can be silent. Pinging under load has several possible causes and does not prove the sensor is bad.", "feel": "Less pulling power if ignition timing is held back.", "seeSmell": "Usually no distinctive visible or smell clue.", "driverQuote": "It feels flat on hills and the engine light came on.", "possibleCauses": [ "Internal sensor fault", "Corroded connection or damaged wiring", "Incorrect mounting", "Real combustion knock from a separate engine or fuel issue" ], "ifIgnored": "Poor performance may continue; actual persistent knock can damage internal engine parts.", "diagnosis": "A technician checks codes, mounting, wiring and the vibration signal, and distinguishes real knock from signal faults.", "urgency": "soon", "relatedIds": [ "ignition-spark-plugs", "engine-pistons-rings", "engine-valves", "fuel-air-injectors" ], "sourceIds": [ "pt-knock", "pt-plugwear" ] }, { "id": "ignition-throttle-body", "name": "Electronic throttle body and position sensor", "does": "Where equipped, a computer-controlled valve meters incoming air and reports its actual opening.", "notice": "Unstable idle, slow response, stalling or a reduced-power warning.", "hear": "No reliable distinctive failure sound.", "feel": "Hesitation, surging or less acceleration than requested.", "seeSmell": "A warning light may appear; deposits or connector damage may be found during inspection.", "driverQuote": "I press the pedal, but the engine barely responds.", "possibleCauses": [ "Throttle actuator fault", "Position-signal fault", "Deposits or mechanical sticking", "Wiring or power-supply problems" ], "ifIgnored": "Unpredictable response or stalling can make driving unsafe. Stop if acceleration control is unreliable.", "diagnosis": "Compare commanded and actual throttle position, inspect the air path and wiring, and follow any model-specific relearn procedure.", "urgency": "soon", "relatedIds": [ "ignition-pedal-sensor", "fuel-air-maf-sensor", "fuel-air-map-sensor", "fuel-air-intake-manifold" ], "sourceIds": [ "pt-throttle", "pt-tps" ] }, { "id": "ignition-pedal-sensor", "name": "Accelerator pedal position sensor", "does": "Where equipped, sends the driver's accelerator request to the engine computer; it does not directly open the throttle.", "notice": "Reduced-power operation, little response to the pedal or an unusually high idle.", "hear": "No distinctive sensor sound.", "feel": "The engine may not respond normally as the pedal moves.", "seeSmell": "A warning lamp may be the only visible sign.", "driverQuote": "The pedal moves normally, but the car has stopped responding to it.", "possibleCauses": [ "Sensor electronics fault", "Missing power or ground", "Harness or connector damage" ], "ifIgnored": "Loss of reliable accelerator response can leave the car unable to keep pace safely. Stop if control is unreliable.", "diagnosis": "A technician compares pedal signals through their range and checks wiring, supply and grounds before condemning the assembly.", "urgency": "soon", "relatedIds": [ "ignition-throttle-body" ], "sourceIds": [ "pt-pedal" ] } ] }, { "id": "brakes", "name": "Brakes", "summary": "Hydraulic pressure squeezes friction material against rotating discs to slow the car. Assist reduces pedal effort; ABS and stability control manage pressure when grip changes. Equipment varies. These are symptom possibilities, not confirmed diagnoses. Stop means stop safely and arrange assistance; soon means prompt inspection; inspect means arrange a routine check unless symptoms worsen.", "components": [ { "id": "brakes-pads", "name": "Brake pads", "does": "Press friction material against the discs to turn motion into heat.", "notice": "Braking noise, a wear message or reduced stopping performance.", "hear": "Squeal can be a wear indicator; persistent grinding needs immediate attention.", "feel": "Stopping may need more effort or feel uneven.", "seeSmell": "Thin friction material or a hot, acrid smell after overheating.", "driverQuote": "It squeals every time I slow down.", "possibleCauses": [ "Normal pad wear", "Sticking caliper", "Contamination or incorrect hardware" ], "ifIgnored": "Worn friction material can damage discs and reduce braking.", "diagnosis": "A technician measures inner and outer pads and checks discs, hardware and caliper movement. Stop if grinding accompanies weak braking.", "urgency": "soon", "relatedIds": [ "brakes-rotors", "brakes-calipers", "brakes-slide-pins" ], "sourceIds": [ "ch-pads", "ch-brake-noise" ] }, { "id": "brakes-rotors", "name": "Brake discs (rotors)", "does": "Rotate with the wheels, providing the braking surface and dispersing heat.", "notice": "Pulsation during braking or worsening stopping performance.", "hear": "Scraping or intermittent rubbing may accompany surface damage.", "feel": "A rhythmic pedal pulse or steering shake during ordinary stops.", "seeSmell": "Grooves, cracks, heavy corrosion or heat discoloration; appearance alone is insufficient.", "driverQuote": "The steering wheel shakes when I brake.", "possibleCauses": [ "Disc thickness variation or runout", "Uneven friction deposits", "Hub contamination or dragging caliper" ], "ifIgnored": "Thin or damaged discs lose heat capacity and can crack.", "diagnosis": "A shop measures thickness, variation and runout, then checks the hub and caliper. Severe vibration or braking loss requires stopping.", "urgency": "soon", "relatedIds": [ "brakes-pads", "wheels-hub", "brakes-calipers", "wheels-bearing", "suspension-arm-bushings" ], "sourceIds": [ "ch-rotors", "ch-brake-noise", "ch-bearings", "ch-control-arms", "qa-disc-damage" ] }, { "id": "brakes-calipers", "name": "Brake calipers and piston seals", "does": "Convert fluid pressure into the force that clamps the pads.", "notice": "The car pulls while braking, a wheel drags or fluid leaks.", "hear": "Rubbing or grinding can come from the pads; no unique caliper sound.", "feel": "Uneven braking or resistance while rolling.", "seeSmell": "Fluid near a caliper, uneven pad wear or an overheated-brake smell.", "driverQuote": "It pulls left when I stop, and that corner smells hot.", "possibleCauses": [ "Sticking piston or damaged seal", "Seized guides", "Restricted hose or pad binding" ], "ifIgnored": "Dragging overheats pads and discs; leaks can reduce hydraulic braking.", "diagnosis": "A technician compares brake action, checks leaks and tests movement and pressure release. Stop for leakage, smoke or reduced braking.", "urgency": "soon", "relatedIds": [ "brakes-hoses", "brakes-slide-pins", "brakes-pads", "wheels-tires", "suspension-arm-bushings" ], "sourceIds": [ "ch-calipers", "ch-caliper-check", "ch-steering-diagnosis", "ch-control-arms" ] }, { "id": "brakes-slide-pins", "name": "Caliper slide pins and pad hardware", "does": "Let a floating caliper center over the disc and keep pads correctly supported.", "notice": "Uneven pad wear or noise that returns after a brake service.", "hear": "Rattle, squeal or a click as braking begins.", "feel": "Possible drag or uneven response; sometimes nothing noticeable.", "seeSmell": "Damaged rubber boots, corrosion or one pad wearing faster.", "driverQuote": "The pads are new, but the brake still rattles.", "possibleCauses": [ "Corroded or seized guides", "Worn or misplaced clips", "Incorrect lubricant or damaged boots" ], "ifIgnored": "Pads can bind, wear unevenly and overheat the disc.", "diagnosis": "A technician checks free movement, boots, contact points and the correct hardware for the caliper design.", "urgency": "soon", "relatedIds": [ "brakes-calipers", "brakes-pads", "brakes-rotors" ], "sourceIds": [ "ch-slide-pins", "ch-calipers" ] }, { "id": "brakes-lines", "name": "Rigid brake lines", "does": "Carry pressurized brake fluid between the master cylinder, ABS unit and wheel circuits.", "notice": "A falling fluid level, brake warning or sudden pedal change.", "hear": "Usually no distinctive sound.", "feel": "A low or sinking pedal if pressure escapes.", "seeSmell": "Wet patches, severe corrosion or damaged tubing underneath the car.", "driverQuote": "The brake pedal suddenly went much farther down.", "possibleCauses": [ "Corrosion perforation", "Impact or chafing damage", "Leaking fitting" ], "ifIgnored": "A leak can cause major loss of braking in the affected circuit.", "diagnosis": "Stop safely and arrange recovery for suspected leakage or changed braking. A professional inspects the complete line routing and hydraulic pressure retention.", "urgency": "stop", "relatedIds": [ "brakes-hoses", "brakes-master-cylinder", "brakes-fluid" ], "sourceIds": [ "ch-lines", "ch-master" ] }, { "id": "brakes-hoses", "name": "Flexible brake hoses", "does": "Carry brake pressure across moving steering and suspension joints.", "notice": "Brake pull, a dragging wheel, leakage or a soft pedal.", "hear": "Usually silent; surrounding brakes may rub.", "feel": "Delayed brake release or inconsistent pedal response.", "seeSmell": "Cracks, swelling or wetness around hose ends; internal restrictions may be invisible.", "driverQuote": "One brake stays on after I release the pedal.", "possibleCauses": [ "Internal hose deterioration", "External damage or twisting", "Leaking crimp or connection" ], "ifIgnored": "Leakage reduces braking; trapped pressure can overheat a wheel brake.", "diagnosis": "A technician checks hose condition and pressure release against caliper faults. Stop for leakage, smoke or altered stopping ability.", "urgency": "soon", "relatedIds": [ "brakes-lines", "brakes-calipers", "brakes-master-cylinder" ], "sourceIds": [ "ch-hoses", "ch-lines", "ch-caliper-check" ] }, { "id": "brakes-master-cylinder", "name": "Brake master cylinder", "does": "Turns pedal force into hydraulic pressure for the brake circuits.", "notice": "The pedal sinks under steady pressure or braking becomes inconsistent.", "hear": "No distinctive sound is expected.", "feel": "A soft, low or gradually sinking pedal.", "seeSmell": "Fluid loss may be visible, but an internal pressure leak may leave no puddle.", "driverQuote": "My foot keeps going down while I am holding the brake.", "possibleCauses": [ "Internal seal bypass", "Air in the hydraulic system", "External leak or another circuit fault" ], "ifIgnored": "Available brake pressure and stopping ability can deteriorate.", "diagnosis": "Stop safely and arrange assistance. A technician tests pressure retention and isolates the cause using the vehicle's service procedure.", "urgency": "stop", "relatedIds": [ "brakes-fluid", "brakes-lines", "brakes-abs-unit" ], "sourceIds": [ "ch-master", "ch-caliper-check" ] }, { "id": "brakes-booster", "name": "Brake booster and vacuum supply", "does": "On vacuum-assisted systems, multiplies pedal force using engine or pump vacuum.", "notice": "Braking suddenly requires much more leg effort.", "hear": "A new persistent hiss may suggest a vacuum leak, but is not conclusive.", "feel": "An unusually hard brake pedal while the engine is running.", "seeSmell": "Often no visible sign; a warning depends on the vehicle.", "driverQuote": "The pedal is hard and I have to push much harder.", "possibleCauses": [ "Booster leak", "Damaged vacuum hose or check valve", "Insufficient engine or pump vacuum" ], "ifIgnored": "Higher pedal effort can increase stopping distance.", "diagnosis": "Stop safely if braking effort changes. A professional measures vacuum supply and retention and checks assist; some cars use electric or hydraulic boosters instead.", "urgency": "stop", "relatedIds": [ "brakes-vacuum-pump", "brakes-master-cylinder" ], "sourceIds": [ "ch-booster", "ch-vacuum" ] }, { "id": "brakes-vacuum-pump", "name": "Brake vacuum pump, where equipped", "does": "Supplies extra vacuum when engine vacuum cannot provide sufficient brake assist.", "notice": "An assist warning or unexpectedly heavy braking effort.", "hear": "A brief operating hum can be normal; sound alone cannot prove failure.", "feel": "A harder pedal if vacuum supply is inadequate.", "seeSmell": "Usually no visible sign; damaged wiring or hoses may be found during inspection.", "driverQuote": "The brake assist warning appeared, and the pedal feels heavy.", "possibleCauses": [ "Pump motor fault", "Power supply or control fault", "Leaking or obstructed vacuum plumbing" ], "ifIgnored": "Assist may remain reduced when it is needed.", "diagnosis": "Stop for reduced assistance. A technician checks stored faults, vacuum pressure, power supply and pump control before replacing it.", "urgency": "stop", "relatedIds": [ "brakes-booster", "brakes-master-cylinder" ], "sourceIds": [ "ch-vacuum" ] }, { "id": "brakes-fluid", "name": "Brake fluid and reservoir", "does": "Transmits hydraulic force and supplies fluid as the braking system operates.", "notice": "Low-fluid warning, changed pedal feel or reduced braking after heat builds.", "hear": "No distinctive sound.", "feel": "A long or soft pedal if air or vapor enters the circuit.", "seeSmell": "Low reservoir level or leaks; fluid color alone cannot establish serviceability.", "driverQuote": "The pedal felt soft after the long downhill.", "possibleCauses": [ "Moisture lowering the boiling point", "Hydraulic leak or trapped air", "Excessive brake heat" ], "ifIgnored": "Boiling or fluid loss can greatly reduce brake pressure.", "diagnosis": "A technician checks leaks, fluid condition and the specified service interval. Stop for a new soft pedal or weak braking; cooling alone does not confirm safety.", "urgency": "soon", "relatedIds": [ "brakes-master-cylinder", "brakes-lines", "brakes-calipers" ], "sourceIds": [ "ch-fluid", "ch-master" ] }, { "id": "brakes-wheel-speed-sensors", "name": "Wheel speed sensors and encoder rings", "does": "Report wheel rotation to ABS, traction and stability-control systems.", "notice": "ABS or stability warnings, sometimes unexpected intervention at low speed.", "hear": "No sensor sound; false intervention may cause pump chatter.", "feel": "Unexpected pedal pulsing, or no change in ordinary braking.", "seeSmell": "Warning lamps; damaged wiring or encoder contamination may be hidden.", "driverQuote": "The ABS light came on, but the brakes still feel normal.", "possibleCauses": [ "Sensor wiring damage", "Encoder ring fault or contamination", "Bearing play or low supply voltage" ], "ifIgnored": "Anti-lock or stability assistance may be unavailable.", "diagnosis": "A technician compares live wheel-speed signals, wiring and encoder condition. A code does not by itself prove the sensor failed.", "urgency": "soon", "relatedIds": [ "brakes-abs-unit", "wheels-bearing", "wheels-hub" ], "sourceIds": [ "ch-speed-sensors" ] }, { "id": "brakes-abs-unit", "name": "ABS hydraulic unit and control module", "does": "Uses valves, a pump and electronics to adjust wheel-brake pressure during ABS and stability events.", "notice": "Persistent ABS or stability warnings or unusual intervention.", "hear": "Brief pump chatter during genuine ABS operation can be normal.", "feel": "Pulsation during hard braking can be normal; unexpected pulses need assessment.", "seeSmell": "Warning lamps; hydraulic leakage is not normal.", "driverQuote": "The ABS warning stays on after the car starts.", "possibleCauses": [ "Supply or wiring fault", "Incorrect sensor input", "Internal hydraulic or electronic fault" ], "ifIgnored": "ABS or stability control may be disabled, even if basic braking remains.", "diagnosis": "A professional reads faults and tests inputs, power, hydraulics and commanded functions. Stop for red brake warnings with changed braking or leakage.", "urgency": "soon", "relatedIds": [ "brakes-wheel-speed-sensors", "brakes-fluid", "steering-torque-angle-sensor" ], "sourceIds": [ "ch-abs", "ch-speed-sensors" ] }, { "id": "brakes-parking-brake", "name": "Parking brake mechanism or electric actuator", "does": "Holds the parked vehicle using a mechanical or electrically operated brake mechanism.", "notice": "It will not hold, will not release or shows a parking-brake fault.", "hear": "A short motor sound can be normal on electric systems; persistent grinding is not.", "feel": "Drag if it remains applied; the control may feel different on cable systems.", "seeSmell": "Warning message or overheated-brake smell if driven while dragging.", "driverQuote": "The parking brake says released, but the car feels held back.", "possibleCauses": [ "Actuator or wiring fault", "Seized caliper mechanism", "Cable or adjustment problem where fitted" ], "ifIgnored": "The car may roll while parked or the brakes may overheat.", "diagnosis": "A technician verifies holding and release, checks faults and follows the required service mode. Do not drive with a stuck or overheating brake.", "urgency": "soon", "relatedIds": [ "brakes-calipers", "brakes-pads" ], "sourceIds": [ "ch-parking", "ch-handbrake-cable" ] } ] }, { "id": "steering", "name": "Steering", "summary": "The steering wheel, shaft, steering gear and tie rods turn the road wheels. Many cars use electric assistance. Hydraulic pumps, fluid and hoses apply only where fitted. New binding, major looseness or unpredictable assistance calls for stopping safely.", "components": [ { "id": "steering-rack", "name": "Steering rack and pinion", "does": "Converts steering-wheel rotation into sideways movement of the tie rods.", "notice": "Wandering, uneven turning effort or poor return toward center.", "hear": "Possible knocking when changing steering direction.", "feel": "Play, binding or inconsistent response.", "seeSmell": "Hydraulic racks may leak; electric racks do not use power-steering fluid.", "driverQuote": "I turn the wheel a little before the car responds.", "possibleCauses": [ "Internal gear wear", "Loose mounts or tie rods", "Assist fault or binding suspension joint" ], "ifIgnored": "Steering precision and vehicle control can worsen.", "diagnosis": "A technician separates mechanical play from assist faults and checks alignment. Stop if steering binds or cannot be controlled predictably.", "urgency": "soon", "relatedIds": [ "steering-eps", "steering-inner-tie-rods", "steering-rack-mounts" ], "sourceIds": [ "ch-eps-rack", "ch-steering-diagnosis" ] }, { "id": "steering-eps", "name": "Electric power-steering motor and module", "does": "Adds steering assistance through a motor on the rack or column, depending on design.", "notice": "An EPS warning or intermittent loss of assistance.", "hear": "No reliable failure sound; some electric motor sound is normal.", "feel": "Unexpectedly heavy steering, especially during parking.", "seeSmell": "Steering-assist message, usually without an external leak.", "driverQuote": "The wheel suddenly became really heavy in the parking lot.", "possibleCauses": [ "Motor or control-module fault", "Low system voltage", "Sensor, wiring or calibration fault" ], "ifIgnored": "Assistance may fail again or remain unavailable.", "diagnosis": "A technician checks power, grounds, faults and live inputs before condemning the motor. Stop safely for sudden or unpredictable changes in steering effort.", "urgency": "stop", "relatedIds": [ "steering-rack", "steering-torque-angle-sensor", "steering-column-joints" ], "sourceIds": [ "ch-eps" ] }, { "id": "steering-torque-angle-sensor", "name": "Steering torque and angle sensors", "does": "Measure driver steering effort and wheel position for assistance and stability systems; designs may combine these functions.", "notice": "EPS or stability warnings, or abnormal steering assistance.", "hear": "No distinctive sensor sound.", "feel": "Assistance may feel uneven, jittery or reluctant to return toward center.", "seeSmell": "Warning lamps, usually no visible damage.", "driverQuote": "The wheel sometimes twitches and the steering warning appears.", "possibleCauses": [ "Sensor signal fault", "Wiring or voltage problem", "Lost calibration or incorrect setup" ], "ifIgnored": "Steering assistance or stability functions may be impaired.", "diagnosis": "A technician checks live torque and angle values against actual movement and verifies calibration. Stop for unwanted steering movement.", "urgency": "soon", "relatedIds": [ "steering-eps", "brakes-abs-unit", "steering-rack" ], "sourceIds": [ "ch-steering-sensors", "ch-eps-rack", "ch-eps" ] }, { "id": "steering-inner-tie-rods", "name": "Inner tie rods", "does": "Transfer rack movement to the outer tie rods while allowing suspension movement.", "notice": "Wandering, an off-center steering wheel or uneven tire wear.", "hear": "Possible knock when steering direction reverses.", "feel": "Loose response or vibration through the wheel.", "seeSmell": "Tire wear may be visible; the inner joint is usually covered by a bellows.", "driverQuote": "I keep making little corrections to stay straight.", "possibleCauses": [ "Inner-joint wear", "Rack wear or loose mounting", "Impact damage or incorrect alignment" ], "ifIgnored": "Wheel alignment and steering accuracy can deteriorate.", "diagnosis": "A technician identifies exactly which joint has play and checks alignment after repair. Major looseness requires stopping.", "urgency": "soon", "relatedIds": [ "steering-outer-tie-rods", "steering-rack", "wheels-tires" ], "sourceIds": [ "ch-inner-tie" ] }, { "id": "steering-outer-tie-rods", "name": "Outer tie-rod ends", "does": "Connect the steering linkage to the steering knuckles through pivoting joints.", "notice": "Imprecise steering, poor tracking or rapid edge wear on tires.", "hear": "Clunking or knocking during low-speed turns.", "feel": "Steering looseness or vibration.", "seeSmell": "A torn joint boot or uneven tread may be visible.", "driverQuote": "It clunks when I turn slowly, and the steering feels loose.", "possibleCauses": [ "Joint wear", "Contamination through a damaged boot", "Pothole or collision damage" ], "ifIgnored": "Severe wear can lead to joint separation and loss of directional control.", "diagnosis": "A professional checks joint movement, boots and adjacent linkage. Stop if control is poor or looseness is pronounced.", "urgency": "soon", "relatedIds": [ "steering-inner-tie-rods", "suspension-ball-joints", "wheels-tires" ], "sourceIds": [ "ch-outer-tie" ] }, { "id": "steering-column-joints", "name": "Steering column and intermediate-shaft joints", "does": "Carry rotation from the steering wheel to the steering gear through angled joints.", "notice": "New notches, binding or free play while steering.", "hear": "A click or clunk near the column may occur, but has several possible sources.", "feel": "Uneven resistance or a loose connection.", "seeSmell": "Often no visible sign from the driver's seat.", "driverQuote": "The steering feels stiff at the same point each turn.", "possibleCauses": [ "Corroded or worn shaft joint", "Column bearing problem", "Binding rack or suspension pivot" ], "ifIgnored": "A damaged mechanical connection can compromise steering control.", "diagnosis": "A technician localizes binding and checks vehicle-specific recalls and shaft connections. Stop for binding, sudden play or unreliable response.", "urgency": "stop", "relatedIds": [ "steering-rack", "steering-eps", "suspension-strut-mounts" ], "sourceIds": [ "ch-steering-column", "ch-hydraulic-steering" ] }, { "id": "steering-rack-mounts", "name": "Steering-rack mounts and bushings", "does": "Secure the steering gear to the body or subframe and limit unwanted movement.", "notice": "Steering response seems delayed or changes under load.", "hear": "Possible clunk when steering direction changes or the road is rough.", "feel": "Wandering or movement before the wheels respond.", "seeSmell": "Loose hardware or deteriorated rubber may only be visible on a lift.", "driverQuote": "There is a knock before the steering takes up.", "possibleCauses": [ "Worn mount bushings", "Loose or damaged fasteners", "Internal rack or tie-rod play" ], "ifIgnored": "Unwanted rack movement can worsen steering precision.", "diagnosis": "A technician observes gear mounting movement while checking the complete linkage. Stop for major looseness or loss of steering accuracy.", "urgency": "soon", "relatedIds": [ "steering-rack", "steering-inner-tie-rods", "suspension-arm-bushings" ], "sourceIds": [ "ch-steering-diagnosis", "ch-hydraulic-steering" ] }, { "id": "steering-hydraulic-pump", "name": "Hydraulic power-steering pump, where equipped", "does": "Supplies pressurized fluid to a hydraulic steering gear; electric-only steering has no such pump.", "notice": "Heavy steering or assistance that varies with engine speed.", "hear": "Whine or groan during steering; a belt-driven pump may be associated with squeal.", "feel": "Jerky or reduced assistance.", "seeSmell": "Possible low fluid, foaming or a leak.", "driverQuote": "It groans when I park and the wheel is harder to turn.", "possibleCauses": [ "Low or aerated fluid", "Pump wear or restricted hose", "Drive-belt problem where fitted" ], "ifIgnored": "Pump damage and reduced steering assistance can follow.", "diagnosis": "A professional checks fluid supply, leaks, drive and hydraulic output. Stop for sudden or severe steering difficulty.", "urgency": "soon", "relatedIds": [ "steering-hydraulic-hoses", "steering-rack" ], "sourceIds": [ "ch-hydraulic-steering", "ch-steering-pump" ] }, { "id": "steering-hydraulic-hoses", "name": "Hydraulic steering hoses and fluid, where equipped", "does": "Circulate the specified fluid between reservoir, pump and steering gear.", "notice": "Repeated fluid loss or assistance becoming noisy and inconsistent.", "hear": "Pump whine may result from air entry; the hose itself has no unique sound.", "feel": "Heavy or jerky assistance if supply or flow is impaired.", "seeSmell": "Wet connections, fluid beneath the car or reservoir foaming.", "driverQuote": "The steering fluid keeps dropping and the pump gets noisy.", "possibleCauses": [ "Leaking hose or seal", "Restricted line", "Wrong or contaminated fluid" ], "ifIgnored": "Loss of lubrication can damage the pump and reduce assistance.", "diagnosis": "A shop identifies the fluid and leak source and checks flow restrictions. Stop for severe steering changes or fluid reaching hot components.", "urgency": "soon", "relatedIds": [ "steering-hydraulic-pump", "steering-rack" ], "sourceIds": [ "ch-hydraulic-steering" ] } ] }, { "id": "suspension", "name": "Suspension", "summary": "Springs carry vehicle weight; dampers control movement. Arms, joints and bushings locate each wheel. Layouts vary, so a car may use struts, separate shocks or several links. A noise alone cannot identify the failed part.", "components": [ { "id": "suspension-dampers", "name": "Shock absorbers and strut dampers", "does": "Control spring movement so the tires stay in consistent contact with the road. A strut also forms part of the wheel-locating structure.", "notice": "Repeated bouncing, poor body control or worsening tire wear.", "hear": "Clunks often involve mounts or nearby parts, not necessarily the damper.", "feel": "Floating, excess dive or instability over uneven pavement.", "seeSmell": "Heavy wet leakage or damaged rods; light oil mist alone may be normal.", "driverQuote": "The car keeps bouncing after a bump.", "possibleCauses": [ "Damper wear or leakage", "Loose mounting", "Tire or spring problem" ], "ifIgnored": "Road contact, handling and braking on rough surfaces can worsen.", "diagnosis": "A technician assesses damping, mounts, tires and leakage together.", "urgency": "soon", "relatedIds": [ "suspension-strut-mounts", "suspension-springs", "wheels-tires" ], "sourceIds": [ "ch-shocks", "ch-shock-leaks" ] }, { "id": "suspension-springs", "name": "Coil springs", "does": "Carry vehicle weight and absorb road movement while maintaining ride height.", "notice": "One corner sits low or the car bottoms out more easily.", "hear": "A broken or displaced coil may clunk or scrape; sagging may be silent.", "feel": "Reduced suspension travel or a harsh impact over dips.", "seeSmell": "Uneven stance, corrosion or a broken coil visible during inspection.", "driverQuote": "That side of the car looks lower than the other.", "possibleCauses": [ "Broken or weakened spring", "Excessive load", "Incorrect spring or damaged seat" ], "ifIgnored": "Changed ride height can affect alignment and tire clearance.", "diagnosis": "A professional measures ride height and inspects coils and seats. Stop for tire contact, a displaced spring or unstable handling.", "urgency": "soon", "relatedIds": [ "suspension-dampers", "suspension-bump-stops", "wheels-tires" ], "sourceIds": [ "ch-springs" ] }, { "id": "suspension-strut-mounts", "name": "Strut top mounts and bearings", "does": "Attach a strut to the body; steering-strut bearings let the assembly rotate smoothly.", "notice": "Noise over bumps or resistance during steering.", "hear": "Clunks over bumps or creaking while turning.", "feel": "Notchy steering or impacts transmitted into the body.", "seeSmell": "Cracked rubber or displaced mounting parts may be found during inspection.", "driverQuote": "It creaks when I turn, even at low speed.", "possibleCauses": [ "Worn top bearing", "Deteriorated mount", "Loose hardware or another suspension joint" ], "ifIgnored": "Movement can damage mounts and affect steering or ride quality.", "diagnosis": "A technician distinguishes bearing noise from loose mounting and nearby joints. Stop if steering binds or the assembly is visibly displaced.", "urgency": "soon", "relatedIds": [ "suspension-dampers", "steering-column-joints", "suspension-ball-joints" ], "sourceIds": [ "ch-strut-mounts" ] }, { "id": "suspension-control-arms", "name": "Control arms and wheel-locating links", "does": "Guide wheel travel and hold wheel position relative to the body; number and shape vary by suspension design.", "notice": "Pulling, poor tracking or tire wear after an impact.", "hear": "A clunk over bumps or during load changes.", "feel": "Vague steering or a shift in direction over uneven pavement.", "seeSmell": "Bent metal, serious corrosion or unusual wheel position.", "driverQuote": "It started pulling after I hit that pothole.", "possibleCauses": [ "Bent or corroded arm", "Worn attached bushing", "Ball-joint or alignment fault" ], "ifIgnored": "Wheel geometry can change, and structural failure can compromise control.", "diagnosis": "A technician checks the arm, attachments and alignment. Stop for obvious deformation or unstable handling.", "urgency": "soon", "relatedIds": [ "suspension-arm-bushings", "suspension-ball-joints", "wheels-rims" ], "sourceIds": [ "ch-control-arms" ] }, { "id": "suspension-arm-bushings", "name": "Control-arm bushings", "does": "Allow controlled arm movement while cushioning vibration and holding wheel position under load.", "notice": "Clunks, wandering or changing direction when braking or accelerating.", "hear": "A dull knock or creak can occur.", "feel": "The wheel may seem to shift before settling.", "seeSmell": "Separated rubber or movement at the sleeve; shallow surface marks alone need interpretation.", "driverQuote": "It gives a little clunk when I get on and off the brake.", "possibleCauses": [ "Rubber fatigue or separation", "Impact or installation damage", "Loose mounting or adjacent joint wear" ], "ifIgnored": "Excess movement can worsen tire wear and handling.", "diagnosis": "A professional checks bushing movement under appropriate loading and compares it with the design's allowable compliance.", "urgency": "soon", "relatedIds": [ "suspension-control-arms", "suspension-ball-joints", "steering-rack-mounts", "brakes-rotors", "wheels-hub" ], "sourceIds": [ "ch-arm-bushings", "ch-control-arms", "qa-disc-damage" ] }, { "id": "suspension-ball-joints", "name": "Suspension ball joints", "does": "Provide pivots between control arms and wheel carriers while supporting their designed loads.", "notice": "Clunks, steering stiffness or looseness, sometimes uneven tire wear.", "hear": "A knock over dips or while turning.", "feel": "Shimmy or a change in direction over bumps.", "seeSmell": "A damaged dust boot or edge wear on a tire.", "driverQuote": "The front end knocks over bumps and feels less steady.", "possibleCauses": [ "Ball-and-socket wear", "Contamination after boot damage", "Impact damage or another loose joint" ], "ifIgnored": "Severe wear can let a joint separate and cause loss of control.", "diagnosis": "A technician measures play using the correct loaded or unloaded procedure for that suspension. Stop for major looseness or poor control.", "urgency": "soon", "relatedIds": [ "suspension-control-arms", "steering-outer-tie-rods", "wheels-tires" ], "sourceIds": [ "ch-ball-joints" ] }, { "id": "suspension-sway-links", "name": "Anti-roll-bar end links", "does": "Connect the anti-roll bar to the suspension so it can resist body lean.", "notice": "A new rattle over small bumps or less settled cornering.", "hear": "Metallic clunking or knocking on uneven pavement.", "feel": "Possible extra lean or instability if a link is badly worn or disconnected.", "seeSmell": "Broken link, worn joint boot or damaged bushings.", "driverQuote": "There is a light rattle over every little bump.", "possibleCauses": [ "Worn link joints", "Broken link or loose fastening", "Bar-bushing or strut-mount wear" ], "ifIgnored": "The anti-roll bar may become less effective and handling can change.", "diagnosis": "A technician checks links and neighboring components under the correct suspension loading.", "urgency": "soon", "relatedIds": [ "suspension-sway-bushings", "suspension-strut-mounts", "suspension-ball-joints" ], "sourceIds": [ "ch-sway-links" ] }, { "id": "suspension-sway-bushings", "name": "Anti-roll-bar mounting bushings", "does": "Support the bar at the body or subframe while allowing its designed movement.", "notice": "Noise from the bar area over uneven surfaces.", "hear": "Possible squeak or dull knock; links and other joints can sound similar.", "feel": "Often no clear sensation until movement becomes excessive.", "seeSmell": "Deteriorated rubber or shifted brackets may be found during inspection.", "driverQuote": "It squeaks over uneven driveways.", "possibleCauses": [ "Worn bushing fit", "Loose bracket", "Nearby end-link or control-arm wear" ], "ifIgnored": "Unwanted movement and noise may grow and bar control may weaken.", "diagnosis": "A shop checks bracket security and bar movement, then verifies the noise source instead of replacing parts from sound alone.", "urgency": "inspect", "relatedIds": [ "suspension-sway-links", "suspension-arm-bushings" ], "sourceIds": [ "ch-sway-bushings", "ch-steering-diagnosis" ] }, { "id": "suspension-bump-stops", "name": "Bump stops and damper dust boots", "does": "Cushion travel near full compression and protect damper rods from dirt and damage.", "notice": "Harsh impacts on large dips or damaged protective pieces found during service.", "hear": "A hard thump near full suspension compression.", "feel": "Abrupt bottoming rather than a controlled stop to movement.", "seeSmell": "Crumbling bumper material or a split protective boot.", "driverQuote": "Large dips now hit with a much harder thud.", "possibleCauses": [ "Aged or damaged bump stop", "Weak spring or overloading", "Damper or mounting fault" ], "ifIgnored": "Unprotected rods and hard impacts can damage damper seals or internal parts.", "diagnosis": "A technician checks the protection parts together with ride height, load and suspension travel.", "urgency": "inspect", "relatedIds": [ "suspension-dampers", "suspension-springs", "suspension-strut-mounts" ], "sourceIds": [ "ch-protection" ] } ] }, { "id": "wheels", "name": "Wheels and tires", "summary": "Tires provide grip and contain air; wheels, hubs, bearings and fasteners support and locate them. Tire pressure, damage and wheel attachment deserve early attention when investigating vibration. A bulge, flat tire, loose wheel or severe wobble means stop safely.", "components": [ { "id": "wheels-tires", "name": "Tire tread, sidewalls and internal structure", "does": "Carry load through contained air and transmit braking, steering and drive forces to the road.", "notice": "Pressure loss, pulling, vibration or reduced wet grip.", "hear": "Uneven tread can roar; structural damage can thump.", "feel": "Wobble, pull or reduced response.", "seeSmell": "Bulges, cuts, exposed cords, low tread or uneven wear.", "driverQuote": "There is a bubble on the side of my tire.", "possibleCauses": [ "Impact or puncture", "Incorrect pressure or worn tread", "Alignment, balance or suspension problems" ], "ifIgnored": "Structural damage or severe underinflation can cause sudden tire failure.", "diagnosis": "A tire professional checks pressure, tread and internal damage as needed. Stop for bulges, exposed cords, a flat or severe vibration.", "urgency": "soon", "relatedIds": [ "wheels-rims", "wheels-valves", "suspension-dampers" ], "sourceIds": [ "ch-tires", "ch-sidewalls" ] }, { "id": "wheels-rims", "name": "Wheel rims and bead seats", "does": "Support the tire, seal its bead and attach the tire assembly to the hub.", "notice": "A slow leak or new vibration after a pothole or curb strike.", "hear": "No unique sound; the tire may thump or an air leak may hiss.", "feel": "Speed-related shake or wobble.", "seeSmell": "Bent rim edge, visible crack or corrosion near the tire seal.", "driverQuote": "The tire loses air since I hit a pothole.", "possibleCauses": [ "Bent or cracked wheel", "Bead-seat corrosion", "Tire, valve or balance problem" ], "ifIgnored": "Air loss and a damaged wheel can compromise tire support.", "diagnosis": "A professional measures wheel runout and locates leaks while inspecting the tire. Stop for cracks, rapid loss or severe wobble.", "urgency": "soon", "relatedIds": [ "wheels-tires", "wheels-balance-weights", "wheels-hub" ], "sourceIds": [ "ch-rim-leaks", "ch-bearings", "ch-wheel-vibration" ] }, { "id": "wheels-hub", "name": "Wheel hub and mounting flange", "does": "Carries the wheel and brake disc; on driven wheels it connects to the axle shaft.", "notice": "Recurring vibration or brake pulsation after wheel-end work.", "hear": "Possible clicking or noise shared with the bearing or axle joint.", "feel": "Wobble or repeated braking vibration.", "seeSmell": "Mounting corrosion or damage may be hidden behind the wheel and disc.", "driverQuote": "The brake vibration came back after the discs were replaced.", "possibleCauses": [ "Damaged flange or bearing fit", "Loss of axle retention", "Contaminated mounting face" ], "ifIgnored": "Poor mounting or retention can damage the bearing and disturb brake alignment.", "diagnosis": "A technician measures hub runout, checks retention and mounting surfaces using vehicle-specific specifications.", "urgency": "soon", "relatedIds": [ "wheels-bearing", "wheels-fasteners", "brakes-rotors" ], "sourceIds": [ "ch-hubs", "ch-brake-noise" ] }, { "id": "wheels-bearing", "name": "Wheel bearing", "does": "Allows the hub to rotate while carrying radial and side loads.", "notice": "A road-speed hum, roughness or wheel-end looseness.", "hear": "Growl or rumble that may change as cornering load changes.", "feel": "Sometimes vibration; early bearing wear may have no noticeable play.", "seeSmell": "Usually no visible sign; some designs can also show an ABS fault.", "driverQuote": "The humming gets louder as the car goes faster.", "possibleCauses": [ "Bearing race damage", "Lubrication or sealing failure", "Incorrect clamping; tire noise can mimic it" ], "ifIgnored": "Wear can progress to excessive looseness and damage nearby brakes or sensing components.", "diagnosis": "A shop compares noise, bearing condition and tire wear. Sound alone cannot reliably identify the side; stop for severe wobble.", "urgency": "soon", "relatedIds": [ "wheels-hub", "wheels-tires", "brakes-wheel-speed-sensors" ], "sourceIds": [ "ch-bearings", "ch-speed-sensors" ] }, { "id": "wheels-valves", "name": "Tire valve stems, cores and seals", "does": "Provide the inflation connection and seal air inside the tire.", "notice": "A tire repeatedly needs air even without an obvious puncture.", "hear": "A larger leak may hiss; slow leakage is often silent.", "feel": "Usually nothing until pressure becomes low enough to affect handling.", "seeSmell": "Cracked rubber, corroded metal or a missing cap.", "driverQuote": "I keep adding air to the same tire.", "possibleCauses": [ "Aged stem or leaking core", "Damaged TPMS sealing parts", "Puncture or wheel-bead leak" ], "ifIgnored": "Pressure loss can cause tire damage and poor control.", "diagnosis": "A tire shop leak-tests the valve and the rest of the assembly. Rapid loss or a visibly low tire requires stopping.", "urgency": "soon", "relatedIds": [ "wheels-tpms", "wheels-tires", "wheels-rims" ], "sourceIds": [ "ch-tire-care", "ch-tpms" ] }, { "id": "wheels-tpms", "name": "Tire-pressure monitoring sensors", "does": "On direct systems, transmit tire pressure to the car. Indirect systems estimate pressure changes using wheel-speed data.", "notice": "A warning lamp, missing pressure reading or implausible display.", "hear": "No distinctive sound.", "feel": "None from the sensor itself; actual low pressure can change handling.", "seeSmell": "A flashing warning may indicate a system fault; consult the vehicle manual.", "driverQuote": "One tire pressure shows dashes instead of a number.", "possibleCauses": [ "Sensor battery or damage", "Incorrect sensor or relearn issue", "Actual low pressure or receiver fault" ], "ifIgnored": "Automatic pressure warnings may be unreliable.", "diagnosis": "A shop verifies pressures with a gauge, then checks sensor transmissions, IDs and faults. Never assume a pressure warning is only a sensor problem.", "urgency": "soon", "relatedIds": [ "wheels-valves", "wheels-tires", "brakes-wheel-speed-sensors" ], "sourceIds": [ "ch-tpms", "ch-tpms-types" ] }, { "id": "wheels-fasteners", "name": "Wheel nuts, bolts and studs", "does": "Clamp the wheel securely against its mounting surface.", "notice": "A new wobble or clicking after wheel removal, or a missing fastener.", "hear": "Clicking or knocking may occur, but looseness can also be silent.", "feel": "Wheel shake that may change during braking or cornering.", "seeSmell": "Missing or damaged fasteners or movement at the wheel.", "driverQuote": "The wheel started wobbling after the tire change.", "possibleCauses": [ "Incorrect tightening or seating", "Wrong fastener design", "Damaged threads or mounting-face contamination" ], "ifIgnored": "The wheel can loosen further or separate.", "diagnosis": "Stop safely for suspected loose attachment. A professional checks the fasteners, wheel seats, hub and the exact vehicle torque specification.", "urgency": "stop", "relatedIds": [ "wheels-hub", "wheels-rims", "wheels-bearing" ], "sourceIds": [ "ch-fasteners", "ch-bearings" ] }, { "id": "wheels-balance-weights", "name": "Wheel balance weights", "does": "Compensate for uneven mass around the tire and wheel assembly.", "notice": "Vibration in a particular road-speed range, sometimes after tire work.", "hear": "No unique sound from a missing weight.", "feel": "Steering-wheel or seat shake that follows vehicle speed.", "seeSmell": "A missing weight may leave a clean patch; imbalance may have no visible sign.", "driverQuote": "It shakes at highway speed but is smooth around town.", "possibleCauses": [ "Lost or incorrect balance weight", "Tire deformation or uneven wear", "Bent wheel or suspension fault" ], "ifIgnored": "Persistent vibration can accelerate tire and suspension wear.", "diagnosis": "A shop checks tire integrity and attachment, then balance and runout. Severe or sudden vibration requires stopping before assuming simple imbalance.", "urgency": "soon", "relatedIds": [ "wheels-tires", "wheels-rims", "wheels-fasteners" ], "sourceIds": [ "ch-tire-care", "ch-wheel-vibration" ] } ] }, { "id": "axles", "name": "Axles and driveline", "summary": "Differentials and shafts deliver torque to driven wheels. CV joints allow movement without interrupting drive. A front-wheel-drive car may have no long propshaft; rear-wheel-drive and all-wheel-drive layouts may add one, its joints and a center support. Symptoms can overlap with tires, bearings and mounts.", "components": [ { "id": "axles-outer-cv-joints", "name": "Outer CV joints", "does": "Transmit torque at the wheel while accommodating steering and suspension angles.", "notice": "Repeated clicking during a turn, often under power.", "hear": "Rhythmic clicks or knocks; bearing and brake faults can sound similar.", "feel": "Sometimes vibration or a knock during load changes.", "seeSmell": "A split boot or scattered grease may accompany wear.", "driverQuote": "It clicks repeatedly when I turn out of a parking space.", "possibleCauses": [ "Worn joint tracks", "Grease loss or contamination", "Loose attachment or another wheel-end fault" ], "ifIgnored": "Wear can progress to joint failure and loss of drive.", "diagnosis": "A technician checks boots, attachment and joint play and reproduces the sound safely. Stop for heavy banging, binding or severe vibration.", "urgency": "soon", "relatedIds": [ "axles-cv-boots", "axles-halfshafts", "wheels-bearing" ], "sourceIds": [ "ch-cv-axles", "ch-cv-joints" ] }, { "id": "axles-inner-cv-joints", "name": "Inner CV and plunge joints", "does": "Transfer torque while allowing the shaft's effective length to change with suspension travel.", "notice": "Shudder under acceleration or a knock when drive load changes.", "hear": "Possible clunk; there is no unique sound that proves an inner-joint fault.", "feel": "Vibration may change with acceleration rather than engine speed alone.", "seeSmell": "A torn inner boot or grease on nearby surfaces.", "driverQuote": "It shudders when I accelerate, then settles when I ease off.", "possibleCauses": [ "Joint wear or binding", "Bent or incorrect shaft", "Powertrain mount or wheel problem" ], "ifIgnored": "Increasing joint wear can damage the shaft assembly and interrupt drive.", "diagnosis": "A shop compares load-related vibration with joint travel, shaft condition and mounts.", "urgency": "soon", "relatedIds": [ "axles-halfshafts", "axles-cv-boots", "wheels-balance-weights" ], "sourceIds": [ "ch-cv-joints", "ch-cv-noise" ] }, { "id": "axles-cv-boots", "name": "CV-joint boots and clamps", "does": "Keep grease inside each joint and road contamination outside.", "notice": "Grease spots inside a wheel or a boot defect found during service.", "hear": "The boot itself is silent; clicking may begin after the joint wears.", "feel": "Usually no sensation before joint damage develops.", "seeSmell": "Tears, slipped clamps or grease sprayed around the joint.", "driverQuote": "There is thick grease all around the inside of the wheel.", "possibleCauses": [ "Age-related cracking", "Impact or chafing", "Loose clamp or incorrect boot fit" ], "ifIgnored": "Loss of grease and entry of water or grit can ruin the joint.", "diagnosis": "A technician checks sealing and assesses the joint for contamination and wear before deciding what needs replacement.", "urgency": "soon", "relatedIds": [ "axles-outer-cv-joints", "axles-inner-cv-joints", "axles-halfshafts" ], "sourceIds": [ "ch-cv-boots", "ch-cv-axles" ] }, { "id": "axles-halfshafts", "name": "Axle halfshafts (sideshafts)", "does": "Link the differential to each driven wheel through jointed shafts.", "notice": "Vibration after an impact or axle work, or abnormal drive-load noises.", "hear": "Possible clunk or rotating noise; no single sound identifies the shaft.", "feel": "Road-speed vibration that may intensify under power.", "seeSmell": "A bent shaft, damaged joint or loose attachment may be found on a lift.", "driverQuote": "It began vibrating after the axle was replaced.", "possibleCauses": [ "Bent or damaged shaft", "Joint wear", "Incorrect fitment or attachment" ], "ifIgnored": "Vibration and wear can spread to connected joints and wheel-end parts.", "diagnosis": "A professional verifies shaft specification, straightness, joint travel and retention. Stop for severe shaking or banging.", "urgency": "soon", "relatedIds": [ "axles-inner-cv-joints", "axles-outer-cv-joints", "wheels-hub" ], "sourceIds": [ "ch-sideshafts", "ch-cv-service" ] }, { "id": "axles-differential", "name": "Differential gears and bearings", "does": "Deliver torque to driven wheels while allowing different wheel speeds in turns; location depends on drivetrain layout.", "notice": "A whine or rumble that changes with load, or a clunk taking up drive.", "hear": "Howling, humming or gear noise during acceleration, coasting or turns.", "feel": "Possible vibration or binding.", "seeSmell": "Leaks or burnt gear-oil odor may accompany lubrication problems.", "driverQuote": "It howls when I accelerate and changes when I lift off.", "possibleCauses": [ "Gear or bearing wear", "Low or incorrect lubricant", "Incorrect gear setup or driveline play" ], "ifIgnored": "Heat and wear can cause major internal damage.", "diagnosis": "A specialist localizes the noise, checks lubricant and evaluates bearing and gear condition. Stop for binding, grinding or major leakage.", "urgency": "soon", "relatedIds": [ "axles-shaft-seals", "axles-propshaft", "wheels-bearing" ], "sourceIds": [ "ch-differential", "ch-differential-service" ] }, { "id": "axles-shaft-seals", "name": "Differential and axle-shaft seals", "does": "Retain lubricant where shafts enter or leave a differential or transaxle.", "notice": "Fresh oily spots or a wet area around a shaft entry.", "hear": "The seal is silent; a lubricant-starved unit may later whine or grind.", "feel": "Often no early change in driving feel.", "seeSmell": "Oil on the housing or a burnt smell if it reaches hot exhaust parts.", "driverQuote": "There is oil around where the axle enters the gearbox.", "possibleCauses": [ "Aged or damaged sealing lip", "Worn shaft surface or bearing movement", "Installation damage or another nearby leak" ], "ifIgnored": "Low lubricant can overheat gears and bearings; leaked oil can reach hot parts.", "diagnosis": "A professional confirms the fluid and leak origin and checks lubricant level and shaft condition. Stop for substantial leakage, smoke or grinding.", "urgency": "soon", "relatedIds": [ "axles-differential", "axles-halfshafts", "axles-propshaft" ], "sourceIds": [ "ch-axle-seals", "ch-differential-service" ] }, { "id": "axles-propshaft", "name": "Longitudinal driveshaft (propshaft), where equipped", "does": "Carries torque between separated transmission, transfer and axle units in many rear-wheel-drive and all-wheel-drive layouts.", "notice": "Vibration beneath the cabin that follows road speed.", "hear": "Possible drumming or thumping.", "feel": "A buzz or shake through the floor and seat.", "seeSmell": "Dents or damaged attachments may be found underneath.", "driverQuote": "The vibration feels like it is coming through the center floor.", "possibleCauses": [ "Bent or imbalanced shaft", "Joint or support wear", "Incorrect alignment or attachment" ], "ifIgnored": "Vibration can accelerate joint wear and damage surrounding driveline parts.", "diagnosis": "A specialist checks shaft condition, runout, joints and supports. Stop for strong banging or severe vibration.", "urgency": "soon", "relatedIds": [ "axles-propshaft-joints", "axles-center-support", "axles-differential" ], "sourceIds": [ "ch-propshafts", "ch-u-joints" ] }, { "id": "axles-propshaft-joints", "name": "Propshaft universal joints or CV couplings, where equipped", "does": "Transmit rotation across changing angles; the vehicle may use U-joints, CV joints or flexible couplings.", "notice": "Clunks when taking up drive or vibration that increases with speed.", "hear": "A worn U-joint may clunk or produce a speed-related squeak.", "feel": "Driveline shudder or vibration through the body.", "seeSmell": "Joint looseness, damaged seals or coupling damage may be visible during service.", "driverQuote": "There is a clunk when I change from reverse to drive.", "possibleCauses": [ "Joint wear or lubrication failure", "Damaged coupling", "Shaft damage or excessive operating angle" ], "ifIgnored": "Progressive wear can damage the shaft and connected parts.", "diagnosis": "A shop checks the fitted joint type, movement, attachment and shaft geometry. Stop for heavy vibration or banging.", "urgency": "soon", "relatedIds": [ "axles-propshaft", "axles-center-support", "axles-differential" ], "sourceIds": [ "ch-u-joints", "ch-propshafts" ] }, { "id": "axles-center-support", "name": "Propshaft center-support bearing, where equipped", "does": "Supports a multi-piece propshaft and uses an isolating mount to control its position and vibration.", "notice": "Vibration or thumping from the center of the car under drive load.", "hear": "Possible rumble or knock; other driveline parts can sound similar.", "feel": "A shake through the floor, especially as load changes.", "seeSmell": "Damaged support rubber, loose mounting or a displaced shaft.", "driverQuote": "It thumps under the middle of the car as I pull away.", "possibleCauses": [ "Bearing wear", "Torn support rubber", "Misalignment, shaft damage or loose mounting" ], "ifIgnored": "Loss of support can increase shaft movement and stress connected joints.", "diagnosis": "A technician checks support condition and shaft alignment together. Stop for strong banging or visible displacement.", "urgency": "soon", "relatedIds": [ "axles-propshaft", "axles-propshaft-joints" ], "sourceIds": [ "ch-center-bearing", "ch-u-joints" ] } ] }, { "id": "starting", "name": "Starting and charging", "summary": "Typical gasoline-car starting and charging equipment. Designs vary, especially on hybrids and stop-start vehicles. Symptoms guide testing and do not identify a failed part by themselves. Driver quotes are illustrative.", "components": [ { "id": "starting-battery", "name": "12-volt battery", "does": "Stores electricity for starting and vehicle electronics.", "notice": "Slow starting or repeated need for a jump.", "hear": "Slow cranking or rapid clicks.", "feel": "Usually no separate driving sensation.", "seeSmell": "Lights may dim. A swollen or leaking case needs professional attention without handling.", "driverQuote": "It barely turns over in the morning.", "possibleCauses": [ "Battery deterioration", "Charge loss while parked", "Charging fault", "Poor terminal connection" ], "ifIgnored": "The car may not restart.", "diagnosis": "Have battery condition, charge level and charging performance tested; repeated discharge also needs a parked-current check.", "urgency": "soon", "relatedIds": [ "starting-alternator", "starting-cables", "starting-starter" ], "sourceIds": [ "el-battery", "el-battery-causes" ] }, { "id": "starting-starter", "name": "Starter motor and drive", "does": "Turns the engine fast enough to start combustion.", "notice": "No cranking, slow cranking or a motor spinning without turning the engine.", "hear": "Grinding, a whirring motor or silence.", "feel": "Starting is delayed or unavailable.", "seeSmell": "There may be no visible clue.", "driverQuote": "I hear it spin, but the engine does not turn.", "possibleCauses": [ "Worn starter or drive", "Low battery power", "Circuit resistance", "Engine mechanical resistance" ], "ifIgnored": "Starting can fail completely; repeated grinding can damage engagement teeth.", "diagnosis": "A technician compares current draw and cranking speed, checks voltage loss and inspects starter engagement.", "urgency": "soon", "relatedIds": [ "starting-battery", "starting-solenoid", "starting-cables", "starting-grounds", "starting-control-circuit" ], "sourceIds": [ "el-starter", "el-start-tests" ] }, { "id": "starting-solenoid", "name": "Starter solenoid", "does": "Engages the starter drive and switches its main electrical supply.", "notice": "The start request produces no engine rotation.", "hear": "A click, repeated clicks or silence.", "feel": "No distinctive sensation.", "seeSmell": "Usually hidden with the starter.", "driverQuote": "It clicks once when I try to start.", "possibleCauses": [ "Worn solenoid contacts", "Weak battery", "Insufficient control voltage" ], "ifIgnored": "The vehicle can become unable to start.", "diagnosis": "A technician checks available battery power and solenoid engagement, then isolates the starting fault using vehicle-specific procedures.", "urgency": "soon", "relatedIds": [ "starting-starter", "starting-control-circuit", "starting-battery" ], "sourceIds": [ "el-starter", "el-start-chart" ] }, { "id": "starting-alternator", "name": "Alternator and voltage regulator", "does": "Supplies electricity and replenishes the battery while the engine runs.", "notice": "Charging warning or a battery that repeatedly goes flat.", "hear": "Whine or bearing noise may occur.", "feel": "Electrical functions can weaken as charge falls.", "seeSmell": "Charging warning lamp; overheating odor needs immediate attention.", "driverQuote": "The battery light came on while driving.", "possibleCauses": [ "Alternator or regulator fault", "Loose belt", "Damaged wiring", "Battery fault" ], "ifIgnored": "Loss of electrical power can stop the engine. Overcharging can damage electronics.", "diagnosis": "Have charging output, regulation, wiring voltage loss and belt condition checked under load.", "urgency": "soon", "relatedIds": [ "starting-battery", "starting-belt-tensioner", "starting-fuses", "starting-grounds" ], "sourceIds": [ "el-alternator" ] }, { "id": "starting-cables", "name": "Battery cables and terminals", "does": "Carry high starting current between battery and engine.", "notice": "Intermittent starting or slow cranking.", "hear": "Clicks or labored cranking.", "feel": "Usually no separate sensation.", "seeSmell": "Corrosion or damaged insulation; heat or smoke means stop.", "driverQuote": "Sometimes it acts as if the battery is dead.", "possibleCauses": [ "Loose terminal", "Internal cable corrosion", "Damaged connection" ], "ifIgnored": "Resistance can prevent starting or overheat a connection.", "diagnosis": "Have cable connections inspected and voltage loss measured during cranking.", "urgency": "soon", "relatedIds": [ "starting-battery", "starting-starter", "starting-grounds" ], "sourceIds": [ "el-start-tests", "el-battery-causes" ] }, { "id": "starting-grounds", "name": "Engine and body ground straps", "does": "Provide the return path for electrical current.", "notice": "Unrelated electrical faults or intermittent cranking.", "hear": "Starting clicks may accompany poor current flow.", "feel": "No characteristic sensation.", "seeSmell": "A loose, corroded or damaged strap may be visible.", "driverQuote": "The lights and starter both act strangely.", "possibleCauses": [ "Corroded attachment", "Loose connection", "Broken strap", "Internal cable corrosion" ], "ifIgnored": "Starting, charging and electronic functions may fail.", "diagnosis": "A technician checks engine and body ground voltage loss under load and inspects attachment points.", "urgency": "soon", "relatedIds": [ "starting-cables", "starting-alternator", "electrical-connectors" ], "sourceIds": [ "el-ground" ] }, { "id": "starting-fuses", "name": "Starting and charging fuses or fusible links", "does": "Interrupt excessive current in the protected circuits. Exact protection varies by car.", "notice": "Sudden no-crank or no-charge condition.", "hear": "Often silence at a start request.", "feel": "No characteristic sensation.", "seeSmell": "A damaged fuse or heat-marked holder may be found during inspection.", "driverQuote": "Everything worked until that circuit stopped.", "possibleCauses": [ "Shorted wire", "Failed electrical load", "Damaged fuse connection" ], "ifIgnored": "The underlying fault can persist and may overheat wiring.", "diagnosis": "Have the protected circuit and original cause checked. Never fit a higher-rated fuse or bypass protection.", "urgency": "soon", "relatedIds": [ "starting-control-circuit", "starting-alternator", "electrical-fuse-box" ], "sourceIds": [ "el-fuses", "el-alternator" ] }, { "id": "starting-relay", "name": "Starter relay", "does": "Uses the start command to switch power to the starter control circuit.", "notice": "Intermittent or complete failure to crank.", "hear": "A relay may click; that does not prove its contacts work.", "feel": "No characteristic sensation.", "seeSmell": "Usually no visible clue.", "driverQuote": "The dash lights up, but nothing turns.", "possibleCauses": [ "Relay contact wear", "Missing start command", "Supply or wiring fault" ], "ifIgnored": "Starting can fail without warning.", "diagnosis": "A technician checks relay command, supply and switched output against the wiring diagram.", "urgency": "soon", "relatedIds": [ "starting-solenoid", "starting-control-circuit", "electrical-fuse-box" ], "sourceIds": [ "el-start-tests", "el-can" ] }, { "id": "starting-control-circuit", "name": "Start switch and safety interlock circuit", "does": "Passes an authorized start request through the ignition or button and applicable park, neutral, clutch or brake inputs.", "notice": "No crank despite a charged battery.", "hear": "Often silence.", "feel": "No characteristic sensation.", "seeSmell": "A start or key message may appear, depending on equipment.", "driverQuote": "It does not respond when I press Start.", "possibleCauses": [ "Switch or interlock fault", "Connection resistance", "Missing control-module authorization" ], "ifIgnored": "The vehicle may leave you unable to start.", "diagnosis": "Have start-request inputs, interlocks and control voltage checked with vehicle-specific data.", "urgency": "soon", "relatedIds": [ "starting-relay", "starting-solenoid", "electrical-can" ], "sourceIds": [ "el-start-tests", "el-can" ] }, { "id": "starting-belt-tensioner", "name": "Accessory drive belt and tensioner", "does": "Drive the alternator and other accessories while maintaining belt tension.", "notice": "Charging or A/C performance may fall.", "hear": "Squealing, chirping or tensioner rattling.", "feel": "Vibration may accompany a failing drive.", "seeSmell": "Fraying or abnormal belt tracking; worn belts do not always crack.", "driverQuote": "It squeals when I turn on the A/C.", "possibleCauses": [ "Worn belt", "Weak tensioner", "Misaligned pulley", "Worn pulley bearing" ], "ifIgnored": "A lost belt can disable charging and, on some engines, coolant circulation.", "diagnosis": "Have the complete belt drive inspected for wear, alignment, tension and bearing condition. Keep clear of moving belts.", "urgency": "soon", "relatedIds": [ "starting-alternator", "hvac-compressor" ], "sourceIds": [ "el-belt", "el-tensioner" ] } ] }, { "id": "exhaust", "name": "Exhaust and emissions", "summary": "Common gasoline-car exhaust and evaporative-emissions parts. EVAP manages fuel vapor separately from the exhaust pipe. Equipment and sensor layouts vary. Symptoms and illustrative driver quotes are possibilities, not diagnoses.", "components": [ { "id": "exhaust-catalyst", "name": "Catalytic converter", "does": "Chemically reduces harmful pollutants in exhaust gas.", "notice": "Check-engine light or reduced power if flow is restricted.", "hear": "A damaged internal core can rattle.", "feel": "Acceleration may weaken with a blockage.", "seeSmell": "Unusual heat or odor warrants inspection; smell alone cannot identify the cause.", "driverQuote": "The engine runs, but it feels choked when I accelerate.", "possibleCauses": [ "Overheating from misfire or excess fuel", "Oil or coolant contamination", "Impact damage", "An exhaust leak mimicking poor efficiency" ], "ifIgnored": "Restriction or continuing engine faults can worsen damage. Stop for severe power loss or overheating.", "diagnosis": "Have codes, fuel control, leaks, sensor response and exhaust restriction tested before condemning the converter.", "urgency": "soon", "relatedIds": [ "exhaust-oxygen-sensors", "exhaust-pipes", "exhaust-flex-joint", "ignition-ignition-coils", "ignition-spark-plugs", "fuel-air-injectors" ], "sourceIds": [ "el-catalyst", "el-leak-tests", "pt-misfire" ] }, { "id": "exhaust-oxygen-sensors", "name": "Oxygen and air-fuel ratio sensors", "does": "Measure exhaust oxygen for mixture control and catalyst monitoring. Sensor types and roles vary.", "notice": "Check-engine light, poorer economy or uneven running.", "hear": "No characteristic sensor noise.", "feel": "Rough running may accompany a mixture problem.", "seeSmell": "Usually no visible clue from the driver's seat.", "driverQuote": "It uses more fuel and the engine light is on.", "possibleCauses": [ "Sensor contamination", "Heater or wiring fault", "Exhaust leak", "Actual mixture fault" ], "ifIgnored": "Emissions and fuel use may increase; an unresolved mixture problem can harm the catalyst.", "diagnosis": "A technician checks leaks, heater supply and live sensor response using the correct procedure for that sensor type.", "urgency": "soon", "relatedIds": [ "exhaust-catalyst", "exhaust-pipes", "electrical-wiring-harness" ], "sourceIds": [ "el-oxygen", "el-oxygen-tests" ] }, { "id": "exhaust-pipes", "name": "Exhaust pipes and sealed joints", "does": "Route combustion gases through treatment and silencing parts to the outlet.", "notice": "Increased exhaust noise or fumes.", "hear": "Rumbling, ticking or hissing that changes with engine speed.", "feel": "Power can fall when a leak disrupts engine control.", "seeSmell": "Rust, damage or exhaust odor. Dangerous exhaust gases can also be odorless.", "driverQuote": "It is louder, and I smell exhaust inside.", "possibleCauses": [ "Corrosion", "Impact damage", "Cracked weld", "Leaking joint gasket" ], "ifIgnored": "Gas may enter the cabin and leaks may affect sensor readings. Cabin fumes mean stop driving.", "diagnosis": "Have a workshop inspect routing and joints and test for leaks, including temperature-dependent leaks.", "urgency": "soon", "relatedIds": [ "exhaust-flex-joint", "exhaust-hangers", "exhaust-oxygen-sensors" ], "sourceIds": [ "el-leaks", "el-leak-tests" ] }, { "id": "exhaust-muffler", "name": "Muffler and resonator", "does": "Reduce and shape exhaust noise as gases pass toward the tailpipe.", "notice": "New loudness or an altered exhaust tone.", "hear": "Rear-end roaring or an internal rattle.", "feel": "A loose assembly may transmit vibration.", "seeSmell": "Rust holes or damage; cabin exhaust odor means stop.", "driverQuote": "It suddenly sounds much louder at the back.", "possibleCauses": [ "Internal corrosion", "Road impact", "Loose internal tube", "Poor installation" ], "ifIgnored": "Leaks and loose parts may worsen; fumes may reach the cabin.", "diagnosis": "Have the muffler, resonator, joints and nearby supports inspected for leaks, internal damage and clearance.", "urgency": "soon", "relatedIds": [ "exhaust-pipes", "exhaust-hangers" ], "sourceIds": [ "el-muffler" ] }, { "id": "exhaust-hangers", "name": "Exhaust hangers and rubber isolators", "does": "Support the exhaust while allowing movement and reducing vibration into the body.", "notice": "Noise over bumps or after exhaust work.", "hear": "Knocking or rattling underneath.", "feel": "Buzzing through the floor or seat.", "seeSmell": "A low-hanging pipe or split isolator may be visible.", "driverQuote": "It knocks under the car over every bump.", "possibleCauses": [ "Torn rubber isolator", "Broken hanger", "Installation stress", "Misaligned exhaust" ], "ifIgnored": "Extra movement can strain pipes and joints or let the exhaust contact nearby parts.", "diagnosis": "A workshop checks all supports, alignment, clearance and tension in the installed system.", "urgency": "soon", "relatedIds": [ "exhaust-pipes", "exhaust-muffler", "exhaust-flex-joint" ], "sourceIds": [ "el-hangers", "el-exhaust-inspection" ] }, { "id": "exhaust-flex-joint", "name": "Exhaust flex joint", "does": "Allows limited movement between the engine and exhaust pipe.", "notice": "A new leak noise near the front underside.", "hear": "Hissing, rasping or rumbling under acceleration.", "feel": "Vibration may accompany a damaged or strained joint.", "seeSmell": "Damaged braid or a leak may be found; cabin fumes require stopping.", "driverQuote": "It sounds raspy under the front when I accelerate.", "possibleCauses": [ "Fatigue or corrosion", "Impact damage", "Exhaust misalignment" ], "ifIgnored": "Leaks can grow and affect fuel-control readings.", "diagnosis": "Have the flexible section leak-tested and its supports and alignment inspected.", "urgency": "soon", "relatedIds": [ "exhaust-pipes", "exhaust-hangers", "exhaust-oxygen-sensors" ], "sourceIds": [ "el-exhaust-inspection", "el-leak-tests" ] }, { "id": "exhaust-purge-valve", "name": "EVAP purge valve", "does": "Meters stored fuel vapor into the engine when commanded.", "notice": "Engine light or uneven idle.", "hear": "Clicking can be normal operation and is not proof of failure.", "feel": "Rough idle may accompany unwanted vapor or air flow.", "seeSmell": "Fuel odor needs prompt investigation.", "driverQuote": "The idle is uneven and the engine light came on.", "possibleCauses": [ "Sticking valve", "Electrical control fault", "Damaged vapor hose" ], "ifIgnored": "Mixture disturbances or vapor emissions can continue.", "diagnosis": "Have commanded operation, sealing, wiring and vapor lines checked.", "urgency": "soon", "relatedIds": [ "exhaust-charcoal-canister", "exhaust-vent-valve" ], "sourceIds": [ "el-charcoal", "el-evap" ] }, { "id": "exhaust-vent-valve", "name": "EVAP canister vent valve", "does": "Controls the canister air path used in vapor management and leak testing.", "notice": "An EVAP fault may illuminate the engine light.", "hear": "Usually no useful audible warning.", "feel": "Driving may feel normal.", "seeSmell": "Fuel odor may accompany a system leak.", "driverQuote": "It drives normally, but there is an emissions code.", "possibleCauses": [ "Valve fault", "Damaged hose", "Electrical connection fault", "Another EVAP leak" ], "ifIgnored": "Vapor leakage or failed leak monitoring can continue.", "diagnosis": "A technician checks valve operation and uses an approved EVAP leak test to locate the fault.", "urgency": "inspect", "relatedIds": [ "exhaust-charcoal-canister", "exhaust-purge-valve" ], "sourceIds": [ "el-evap" ] }, { "id": "exhaust-charcoal-canister", "name": "EVAP charcoal canister", "does": "Stores fuel vapor until it can be drawn into the engine.", "notice": "Engine light, vapor odor or uneven running.", "hear": "Usually no distinct sound.", "feel": "The car may drive normally.", "seeSmell": "Gasoline odor is possible; persistent strong odor means stop and arrange help.", "driverQuote": "I keep noticing a gasoline smell.", "possibleCauses": [ "Damaged canister", "Leaking vapor line", "Purge-control fault" ], "ifIgnored": "Vapors can escape; loose charcoal can contaminate other EVAP parts.", "diagnosis": "Have the canister, connecting lines and purge operation inspected and leaks tested.", "urgency": "soon", "relatedIds": [ "exhaust-purge-valve", "exhaust-vent-valve", "fuel-air-fuel-pump", "fuel-air-injectors" ], "sourceIds": [ "el-charcoal", "el-evap", "pt-fuelleaksafety", "pt-leaks" ] } ] }, { "id": "hvac", "name": "Heating, ventilation and A/C", "summary": "Common cabin climate components on gasoline cars. Refrigerant, controls and component layout vary. A/C symptoms overlap, so professional pressure, temperature and electrical tests are needed. Driver quotes are illustrative.", "components": [ { "id": "hvac-refrigerant-circuit", "name": "Refrigerant hoses, pipes and seals", "does": "Carry refrigerant and oil through the sealed A/C circuit.", "notice": "Cooling fades or disappears.", "hear": "No reliable sound identifies a leak.", "feel": "Vent air stays warm despite the cooling request.", "seeSmell": "Oil staining can suggest a leak, but locating the source requires professional testing.", "driverQuote": "The air conditioner gets weaker every summer.", "possibleCauses": [ "Leaking seal or hose", "Damaged pipe", "Incorrect previous charge" ], "ifIgnored": "Low refrigerant can reduce cooling and compromise compressor lubrication.", "diagnosis": "An A/C professional identifies the refrigerant, checks for leaks and verifies the specified charge. Do not vent refrigerant or guess the fill amount.", "urgency": "soon", "relatedIds": [ "hvac-compressor", "hvac-condenser", "hvac-evaporator" ], "sourceIds": [ "el-ac-basics", "el-ac-service" ] }, { "id": "hvac-compressor", "name": "A/C compressor", "does": "Circulates and compresses refrigerant to move cabin heat outdoors.", "notice": "Little cooling even with normal blower airflow.", "hear": "Abnormal noise when A/C operates needs investigation.", "feel": "Air remains warm or cooling varies.", "seeSmell": "Usually no visible clue from the cabin.", "driverQuote": "The fan works, but the A/C is warm.", "possibleCauses": [ "Compressor wear", "Electrical or control fault", "Low refrigerant", "Incorrect lubricant or contamination" ], "ifIgnored": "Internal damage can spread contamination through the refrigerant circuit.", "diagnosis": "A professional checks compressor command, drive and pressure response after verifying charge and airflow.", "urgency": "soon", "relatedIds": [ "hvac-refrigerant-circuit", "hvac-condenser", "hvac-expansion-device", "starting-belt-tensioner" ], "sourceIds": [ "el-compressor", "el-ac-basics", "el-ac-service", "el-ac-guide" ] }, { "id": "hvac-condenser", "name": "A/C condenser", "does": "Releases refrigerant heat to outside air, allowing vapor to condense.", "notice": "Poor cooling, sometimes worse at low road speed.", "hear": "No characteristic condenser noise.", "feel": "Vent temperature rises in hot conditions.", "seeSmell": "Debris, damaged fins or leakage may be found at the front of the car.", "driverQuote": "It cools better once I am moving.", "possibleCauses": [ "Blocked airflow", "Refrigerant leak", "Fan fault", "Internal restriction" ], "ifIgnored": "Cooling worsens and the compressor may work under unsuitable conditions.", "diagnosis": "Have condenser condition, airflow, fan operation, refrigerant charge and operating pressures checked together.", "urgency": "soon", "relatedIds": [ "hvac-compressor", "hvac-refrigerant-circuit", "hvac-receiver-drier" ], "sourceIds": [ "el-condenser", "el-ac-guide" ] }, { "id": "hvac-evaporator", "name": "A/C evaporator", "does": "Absorbs heat from cabin air and removes moisture as refrigerant evaporates.", "notice": "Weak cooling, odor or declining airflow during use.", "hear": "Sound alone does not identify an evaporator fault.", "feel": "Air may start cold and later become less effective.", "seeSmell": "Musty odor can arise from contamination; that does not prove a refrigerant leak.", "driverQuote": "It smells musty when the air comes on.", "possibleCauses": [ "Surface contamination", "Refrigerant leak", "Icing caused by another control or flow problem" ], "ifIgnored": "Cooling, air quality and window clearing can deteriorate.", "diagnosis": "Have evaporator airflow, temperature control, drain condition and leak evidence assessed.", "urgency": "inspect", "relatedIds": [ "hvac-cabin-filter", "hvac-expansion-device", "hvac-refrigerant-circuit" ], "sourceIds": [ "el-evaporator", "el-ac-service" ] }, { "id": "hvac-expansion-device", "name": "Expansion valve or orifice tube", "does": "Meters refrigerant into the evaporator and creates the pressure drop needed for cooling.", "notice": "Poor or inconsistent A/C cooling.", "hear": "No single sound confirms a fault.", "feel": "Vent temperature may fluctuate.", "seeSmell": "Usually no visible clue in the cabin.", "driverQuote": "The air switches between cool and warm.", "possibleCauses": [ "Restriction from contamination", "Moisture freezing in the circuit", "Sticking valve", "Another charge or compressor problem" ], "ifIgnored": "Refrigerant flow can remain unsuitable and cooling may fail.", "diagnosis": "An A/C technician compares pressures and temperatures with specifications after checking charge and airflow.", "urgency": "soon", "relatedIds": [ "hvac-evaporator", "hvac-receiver-drier", "hvac-compressor" ], "sourceIds": [ "el-expansion", "el-ac-service" ] }, { "id": "hvac-receiver-drier", "name": "Receiver drier or accumulator", "does": "Filters debris and absorbs moisture. Depending on layout, it also separates liquid from vapor.", "notice": "Cooling may become weak or inconsistent.", "hear": "Usually no distinct warning sound.", "feel": "The symptom is normally changing vent temperature.", "seeSmell": "Often no external clue.", "driverQuote": "The A/C has not worked properly since the system was opened.", "possibleCauses": [ "Moisture saturation", "Internal contamination", "Restricted flow" ], "ifIgnored": "Moisture and debris can affect the expansion device or compressor.", "diagnosis": "Have service history and circuit condition reviewed; replacement requirements depend on the system and repair performed.", "urgency": "soon", "relatedIds": [ "hvac-expansion-device", "hvac-compressor", "hvac-refrigerant-circuit" ], "sourceIds": [ "el-drier", "el-ac-basics" ] }, { "id": "hvac-blower", "name": "Cabin blower and speed controller", "does": "Pushes air through the heater and evaporator; its resistor or electronic controller sets fan speed.", "notice": "No airflow, missing speeds or intermittent operation.", "hear": "Squealing or rattling may change with fan speed.", "feel": "Airflow is weak or absent.", "seeSmell": "A hot electrical smell means switch off the system and arrange inspection.", "driverQuote": "The fan only works on one setting.", "possibleCauses": [ "Worn motor", "Speed controller fault", "Power or wiring problem", "Airflow obstruction" ], "ifIgnored": "Comfort and windshield clearing may be lost.", "diagnosis": "Have blower command, supply, current draw, speed control and the air path checked.", "urgency": "soon", "relatedIds": [ "hvac-cabin-filter", "hvac-blend-door", "electrical-connectors" ], "sourceIds": [ "el-blower", "el-blower-control", "el-voltage-drop" ] }, { "id": "hvac-blend-door", "name": "Blend and mode doors with actuators", "does": "Selects air temperature and directs airflow to dash, floor or windshield outlets.", "notice": "Wrong temperature, unequal zones or air from the wrong outlets.", "hear": "Clicking or grinding behind the dashboard.", "feel": "Air stays hot or cold despite a setting change.", "seeSmell": "Poor defogging may be the visible clue.", "driverQuote": "It clicks behind the dash and stays hot.", "possibleCauses": [ "Worn actuator", "Broken door or linkage", "Obstruction", "Control or calibration issue" ], "ifIgnored": "A jammed door can damage its actuator and reduce windshield clearing.", "diagnosis": "Have the specific door, actuator travel and control signals checked; both moving parts need assessment.", "urgency": "soon", "relatedIds": [ "hvac-blower", "hvac-evaporator", "cooling-heater-core", "cooling-thermostat" ], "sourceIds": [ "el-air-doors", "el-blower-control", "pt-heater", "pt-thermostat" ] }, { "id": "hvac-cabin-filter", "name": "Cabin air filter", "does": "Traps dust and debris in the air entering the cabin ventilation system.", "notice": "Weak airflow or slow window clearing.", "hear": "Blower noise may increase.", "feel": "Less air reaches your face at the same fan setting.", "seeSmell": "Dusty or stale odor can develop.", "driverQuote": "The fan sounds strong, but barely any air comes out.", "possibleCauses": [ "Loaded filter", "Incorrectly fitted filter", "Debris in the air path" ], "ifIgnored": "Airflow and HVAC performance can decline further.", "diagnosis": "Have the filter and air intake inspected using the vehicle's service schedule. A clean filter does not rule out a blower fault.", "urgency": "inspect", "relatedIds": [ "hvac-blower", "hvac-evaporator" ], "sourceIds": [ "el-cabin-filter" ] } ] }, { "id": "electrical", "name": "Vehicle electronics and accessories", "summary": "Common low-voltage wiring, control and accessory components. Actual circuits and network layouts differ by model. Several faults can share one power or ground problem. Illustrative symptoms do not establish a failed module.", "components": [ { "id": "electrical-wiring-harness", "name": "Wiring harness", "does": "Routes power and signals between vehicle components.", "notice": "Intermittent faults or several devices failing together.", "hear": "Audio interference may accompany an electrical fault.", "feel": "A powered accessory may respond slowly.", "seeSmell": "Chafed insulation may be visible. Smoke or burning odor means stop.", "driverQuote": "Several things cut out at the same time.", "possibleCauses": [ "Broken wire", "Chafing", "Corrosion", "Poor previous repair" ], "ifIgnored": "Electrical functions can fail or wiring can overheat.", "diagnosis": "Have the affected circuits traced and tested under load using the correct diagram.", "urgency": "soon", "relatedIds": [ "electrical-connectors", "electrical-fuse-box", "starting-grounds" ], "sourceIds": [ "el-voltage-drop" ] }, { "id": "electrical-connectors", "name": "Electrical connectors and terminals", "does": "Join wiring to components while maintaining electrical contact.", "notice": "A device works intermittently or loses performance.", "hear": "Usually no characteristic sound.", "feel": "Operation may be inconsistent.", "seeSmell": "Corrosion, moisture or heat damage may be found.", "driverQuote": "It works one day and stops the next.", "possibleCauses": [ "Loose terminal", "Water intrusion", "Corrosion", "Damaged terminal grip" ], "ifIgnored": "Resistance or lost contact can disable a circuit.", "diagnosis": "A technician inspects terminal condition and checks voltage loss while the circuit operates.", "urgency": "soon", "relatedIds": [ "electrical-wiring-harness", "electrical-bcm", "starting-grounds" ], "sourceIds": [ "el-voltage-drop", "el-lamps" ] }, { "id": "electrical-bcm", "name": "Body control module", "does": "Coordinates body functions such as lighting, access, wipers and power management, depending on equipment.", "notice": "Several body functions behave unexpectedly.", "hear": "No characteristic module sound.", "feel": "Switch commands may not produce the expected response.", "seeSmell": "Warnings or lights may behave abnormally.", "driverQuote": "The locks and lights have both started acting up.", "possibleCauses": [ "Missing power or ground", "Wiring or network fault", "Configuration problem", "Internal module fault" ], "ifIgnored": "Affected convenience or safety functions can remain unavailable.", "diagnosis": "Have all relevant modules scanned and their supplies, inputs and outputs verified before considering replacement or programming.", "urgency": "soon", "relatedIds": [ "electrical-can", "electrical-fuse-box", "body-safety-lighting" ], "sourceIds": [ "el-bcm", "el-lamps" ] }, { "id": "electrical-can", "name": "CAN communication wiring and gateway", "does": "Allows control modules to exchange messages; a gateway links different networks where fitted.", "notice": "Multiple warnings, lost functions or no start.", "hear": "No distinctive network noise.", "feel": "Behavior depends on which messages are lost.", "seeSmell": "Several warnings may appear together.", "driverQuote": "A bunch of warning lights appeared at once.", "possibleCauses": [ "Shorted or open communication wiring", "Module disrupting communication", "Missing module power", "Gateway fault" ], "ifIgnored": "Required control messages may remain unavailable.", "diagnosis": "A technician checks network fault codes, module power and network signals against the vehicle architecture.", "urgency": "soon", "relatedIds": [ "electrical-bcm", "electrical-wiring-harness", "starting-control-circuit" ], "sourceIds": [ "el-can" ] }, { "id": "electrical-fuse-box", "name": "Fuse box and power distribution connections", "does": "Distributes electrical supply through circuit protection and switching connections.", "notice": "One or several circuits lose power.", "hear": "Relay clicking may be present but is not conclusive.", "feel": "No characteristic sensation.", "seeSmell": "Moisture, corrosion or heat damage can be clues.", "driverQuote": "Several accessories stopped working together.", "possibleCauses": [ "Damaged supply connection", "Corroded terminal", "Blown protective device", "Fault elsewhere in a connected circuit" ], "ifIgnored": "Power loss or overheating may continue.", "diagnosis": "Have circuit protection, supply and terminal condition checked. Preserve specified fuse ratings.", "urgency": "soon", "relatedIds": [ "starting-fuses", "electrical-wiring-harness", "electrical-bcm" ], "sourceIds": [ "el-installation", "el-fuses", "el-voltage-drop" ] }, { "id": "electrical-window-motor", "name": "Power window motor and regulator", "does": "Move and support the door glass.", "notice": "A window stops moving or moves unevenly.", "hear": "Motor noise without normal glass movement may suggest a mechanical issue.", "feel": "The glass may move slowly.", "seeSmell": "Glass may sit unevenly or remain open.", "driverQuote": "I hear the motor, but the window stays put.", "possibleCauses": [ "Motor fault", "Regulator damage", "Missing power", "Broken door wiring" ], "ifIgnored": "The window may become unusable or unsecured.", "diagnosis": "Have switch supply, motor supply, wiring and regulator movement checked. Keep hands clear of the moving mechanism.", "urgency": "soon", "relatedIds": [ "electrical-window-switch", "electrical-wiring-harness" ], "sourceIds": [ "el-window" ] }, { "id": "electrical-window-switch", "name": "Power window switch", "does": "Requests window movement directly or through a control module.", "notice": "A window ignores a switch command.", "hear": "The motor may remain silent.", "feel": "No unusual switch feel is required for an electrical fault.", "seeSmell": "Usually no visible clue.", "driverQuote": "That window does not respond to this button.", "possibleCauses": [ "Switch fault", "Missing supply", "Door wiring fault", "Motor or regulator fault" ], "ifIgnored": "Window operation can remain unavailable.", "diagnosis": "A technician verifies switch power and output, then tests the downstream circuit.", "urgency": "inspect", "relatedIds": [ "electrical-window-motor", "electrical-connectors" ], "sourceIds": [ "el-window" ] }, { "id": "electrical-wiper-motor", "name": "Wiper motor and drive linkage", "does": "Moves the wiper arms across the windshield.", "notice": "Wipers stop, run irregularly or fail to clear their normal sweep.", "hear": "Unusual motor or linkage noise.", "feel": "No characteristic driving sensation.", "seeSmell": "Blades may stop in an abnormal position.", "driverQuote": "The wipers suddenly stopped halfway across.", "possibleCauses": [ "Motor fault", "Linkage problem", "Supply or control fault" ], "ifIgnored": "Visibility can become unsafe in rain or road spray.", "diagnosis": "Have motor command, supply and mechanical drive inspected. Stop driving whenever the windshield cannot be kept clear.", "urgency": "soon", "relatedIds": [ "body-safety-wiper-blades", "electrical-bcm", "electrical-fuse-box" ], "sourceIds": [ "el-wipers", "el-bcm" ] } ] }, { "id": "body-safety", "name": "Body, visibility and occupant safety", "summary": "Common body and restraint components. Equipment and warning meanings vary by vehicle. Follow the owner's manual and obtain professional restraint service. Driver quotes are illustrative, and a warning alone does not identify the failed part.", "components": [ { "id": "body-safety-lighting", "name": "Exterior lamps and lighting controls", "does": "Illuminate the road and show position, braking and intended movement.", "notice": "A lamp fails, flickers or has uneven brightness.", "hear": "No consistent sound identifies a lighting fault.", "feel": "Usually no physical sensation.", "seeSmell": "Dark lamps, failed LED sections or a bulb warning.", "driverQuote": "One of my rear lights keeps flickering.", "possibleCauses": [ "Lamp failure", "Connector corrosion", "Wiring or ground fault", "Control-module fault" ], "ifIgnored": "Other drivers may not see the vehicle or its signals.", "diagnosis": "Have all light functions, connectors, power, ground and control commands checked. Avoid driving when essential lighting is unavailable.", "urgency": "soon", "relatedIds": [ "electrical-connectors", "electrical-bcm", "starting-grounds" ], "sourceIds": [ "el-lamps" ] }, { "id": "body-safety-seat-belts", "name": "Seat belts, buckles and retractors", "does": "Keep occupants restrained and correctly positioned during a crash.", "notice": "A belt does not latch, retract or fit securely.", "hear": "Failure to latch may lack the expected click; sound alone is not a safety test.", "feel": "Excess slack, binding or an insecure buckle.", "seeSmell": "Damaged webbing or twisted routing needs attention.", "driverQuote": "My seat belt will not stay buckled.", "possibleCauses": [ "Damaged buckle or retractor", "Twisted or damaged webbing", "Crash-related damage" ], "ifIgnored": "An occupant may lose essential crash protection. Do not use the affected seat.", "diagnosis": "Have the full belt assembly professionally inspected and follow the manufacturer's replacement requirements.", "urgency": "stop", "relatedIds": [ "body-safety-airbags", "body-safety-srs-module" ], "sourceIds": [ "el-seat-belts", "el-belt-inspection" ] }, { "id": "body-safety-airbags", "name": "Airbag modules", "does": "Supplement seat belts by cushioning occupants in qualifying crashes.", "notice": "Airbag warning or evidence of previous deployment.", "hear": "No normal sound confirms readiness.", "feel": "No driving sensation proves the system works.", "seeSmell": "Deployed or damaged covers require professional assessment.", "driverQuote": "The airbag light stays on after startup.", "possibleCauses": [ "Airbag circuit fault", "Wiring or connector fault", "Prior deployment", "Another restraint-system fault" ], "ifIgnored": "Expected crash protection may be unavailable. A deployed airbag must be replaced before driving again.", "diagnosis": "Arrange prompt specialist restraint diagnosis and check applicable recalls. Do not probe or dismantle airbag circuits.", "urgency": "soon", "relatedIds": [ "body-safety-srs-module", "body-safety-impact-sensors", "body-safety-seat-belts" ], "sourceIds": [ "el-airbags", "el-srs" ] }, { "id": "body-safety-srs-module", "name": "Restraint control module", "does": "Evaluates crash signals, commands appropriate restraints and monitors system faults.", "notice": "Persistent restraint warning.", "hear": "No diagnostic sound.", "feel": "Usually no change in how the car drives.", "seeSmell": "SRS or airbag warning.", "driverQuote": "The restraint warning stays lit.", "possibleCauses": [ "Supply fault", "Wiring fault", "Module fault" ], "ifIgnored": "Restraint operation may be compromised.", "diagnosis": "Arrange immediate professional assessment using manufacturer restraint procedures and stored fault data.", "urgency": "soon", "relatedIds": [ "body-safety-airbags", "body-safety-impact-sensors" ], "sourceIds": [ "el-srs" ] }, { "id": "body-safety-impact-sensors", "name": "Crash and impact sensors", "does": "Report crash forces to the restraint controller.", "notice": "A restraint fault may be the only warning.", "hear": "No diagnostic sound.", "feel": "No reliable driving sensation.", "seeSmell": "SRS warning or collision damage nearby.", "driverQuote": "The airbag warning appeared after a bump.", "possibleCauses": [ "Sensor damage", "Connection fault", "Wiring damage" ], "ifIgnored": "Crash detection may be impaired.", "diagnosis": "A restraint specialist checks codes, wiring and sensor installation using manufacturer procedures.", "urgency": "soon", "relatedIds": [ "body-safety-srs-module", "body-safety-airbags" ], "sourceIds": [ "el-srs" ] }, { "id": "body-safety-door-latch", "name": "Door latch and latch-status switch", "does": "Secures the door and, where fitted, reports whether it is closed.", "notice": "Door will not latch or an ajar warning persists.", "hear": "Unusual wind noise can accompany incomplete closure.", "feel": "The door may not feel securely held.", "seeSmell": "Ajar warning or a door not sitting flush.", "driverQuote": "The door looks closed, but it will not latch properly.", "possibleCauses": [ "Mechanical latch damage", "Latch misalignment", "Status-switch or wiring fault" ], "ifIgnored": "A door that is not fully secured could open while driving.", "diagnosis": "Do not drive with an unsecured door. Have mechanical retention and status reporting checked, including applicable recalls.", "urgency": "stop", "relatedIds": [ "electrical-bcm", "electrical-connectors" ], "sourceIds": [ "el-latch" ] }, { "id": "body-safety-horn", "name": "Horn and horn circuit", "does": "Provides an audible warning to other road users.", "notice": "No horn or unusually weak output.", "hear": "A faint, changed or missing horn note.", "feel": "No characteristic driving sensation.", "seeSmell": "Usually no visible clue.", "driverQuote": "The horn barely makes a sound.", "possibleCauses": [ "Horn unit fault", "Supply or ground problem", "Relay or switch fault" ], "ifIgnored": "An audible warning may be unavailable when needed.", "diagnosis": "Have horn output, circuit supply, relay and switch control checked. Steering-wheel work may involve airbag precautions.", "urgency": "soon", "relatedIds": [ "electrical-fuse-box", "electrical-connectors", "body-safety-airbags" ], "sourceIds": [ "el-horn" ] }, { "id": "body-safety-wiper-blades", "name": "Wiper blades and arms", "does": "Keep the windshield clear by maintaining blade contact with the glass.", "notice": "Streaks, unwiped areas or smearing.", "hear": "Chattering or rubbing.", "feel": "No characteristic driving sensation.", "seeSmell": "Water remains in the viewing area; rubber may be split or hardened.", "driverQuote": "The wipers move, but I still cannot see clearly.", "possibleCauses": [ "Worn rubber", "Damaged blade or arm", "Poor fit or attachment" ], "ifIgnored": "Visibility can become unsafe.", "diagnosis": "Have blade condition, fit and arm contact checked. Stop if rain or spray prevents a clear view.", "urgency": "soon", "relatedIds": [ "electrical-wiper-motor", "body-safety-lighting" ], "sourceIds": [ "el-wipers" ] } ] } ], "symptoms": [ { "id": "engine-oil-pressure-warning", "label": "Oil-pressure warning while the engine runs", "componentIds": [ "engine-oil-pump", "engine-oil-filter", "engine-crankshaft-bearings" ], "urgency": "stop", "guidance": "Stop safely and switch off. A normal oil level does not prove adequate pressure. Arrange diagnosis before continuing.", "sourceIds": [ "pt-warning", "pt-oilpressure" ], "aliases": [ "oil pressure warning", "oil-pressure warning", "oil light", "red oil light", "low oil pressure", "oil warning while driving" ] }, { "id": "engine-heavy-knocking", "label": "New, heavy engine knock", "componentIds": [ "engine-crankshaft-bearings", "engine-oil-pump" ], "urgency": "stop", "guidance": "Stop safely and switch off. Sound alone cannot locate the fault, but continued running risks major damage if lubrication or bearings have failed.", "sourceIds": [ "pt-bearings", "pt-warning" ], "aliases": [ "engine knocking", "engine knock", "knocking engine", "deep engine knock", "heavy knocking", "knock from engine" ] }, { "id": "engine-increasing-oil-use", "label": "Blue exhaust or frequent oil top-ups", "componentIds": [ "engine-pistons-rings", "engine-pcv", "engine-valves" ], "urgency": "soon", "guidance": "Arrange an oil-consumption and leak assessment. Blue smoke can indicate oil burning, but does not identify rings by itself. Stop for an oil-pressure warning.", "sourceIds": [ "pt-pistons", "pt-pcv", "pt-valves" ], "aliases": [ "blue smoke", "blue exhaust smoke", "burning oil", "using oil", "oil consumption", "oil level keeps dropping", "frequent oil top ups" ] }, { "id": "engine-startup-rattle", "label": "Rattle at engine startup", "componentIds": [ "engine-timing-chain", "engine-oil-pump", "transmission-flywheel" ], "urgency": "soon", "guidance": "Have the noise localized promptly. Timing-chain, lubrication and starting-system faults can overlap. Persistent loud mechanical noise needs immediate assessment.", "sourceIds": [ "pt-chain", "pt-dmf" ], "aliases": [ "rattle at startup", "startup rattle", "rattles when starting", "engine rattles on cold start", "timing chain rattle", "engine startup noise" ] }, { "id": "ignition-flashing-light-shaking", "label": "Flashing engine light with shaking", "componentIds": [ "ignition-spark-plugs", "ignition-ignition-coils", "ignition-leads", "fuel-air-injectors", "engine-valves" ], "urgency": "stop", "guidance": "Treat this as a potentially damaging misfire. Stop safely, switch off and arrange assistance. The faulty part cannot be identified from the lamp alone.", "sourceIds": [ "pt-misfire", "pt-coilcheck" ], "aliases": [ "flashing check engine light", "check engine light flashing", "blinking engine light", "engine light and shaking", "engine misfire", "engine shaking badly", "check engine light", "shakes while driving" ] }, { "id": "ignition-cranks-without-starting", "label": "Starter turns, but engine does not start", "componentIds": [ "ignition-crank-sensor", "ignition-cam-sensor", "fuel-air-fuel-pump", "engine-timing-belt" ], "urgency": "soon", "guidance": "Arrange diagnosis of ignition, fuel delivery and mechanical timing. Avoid repeated starting attempts after a sudden mechanical noise or shutdown.", "sourceIds": [ "pt-crank", "pt-cam", "pt-fuelpressure", "pt-belt" ], "aliases": [ "car cranks but won't start", "car cranks but wont start", "cranks but will not start", "cranks but won't start", "cranks no start", "turns over but won't start", "engine turns but won't start", "car won't start", "car wont start", "no start" ] }, { "id": "ignition-repeated-stalling", "label": "Repeated engine stalling", "componentIds": [ "ignition-crank-sensor", "fuel-air-fuel-pump", "ignition-throttle-body", "fuel-air-maf-sensor" ], "urgency": "stop", "guidance": "Move to a safe location and arrange assistance if the car cannot stay running reliably. Several fuel, air and signal faults can cause this.", "sourceIds": [ "pt-crank", "pt-highpump", "pt-throttle", "pt-maf" ], "aliases": [ "engine stalls", "car stalls", "keeps stalling", "dies while driving", "engine cuts out", "stalls at stop lights", "engine stops suddenly" ] }, { "id": "fuel-air-hesitation-under-load", "label": "Hesitation or weak acceleration", "componentIds": [ "fuel-air-fuel-pump", "fuel-air-fuel-filter", "fuel-air-maf-sensor", "fuel-air-air-filter", "ignition-spark-plugs", "ignition-throttle-body" ], "urgency": "soon", "guidance": "Have fuel delivery, air measurement and ignition checked together. Stop if power loss makes traffic unsafe or the engine light flashes with shaking.", "sourceIds": [ "pt-fuelfilter", "pt-fuelpressure", "pt-maf", "pt-airfilter", "pt-plugwear" ], "aliases": [ "hesitates accelerating", "hesitation when accelerating", "car hesitates", "weak acceleration", "losing power", "loss of power", "bogs down", "engine stumbles", "hesitates under load" ] }, { "id": "fuel-air-uneven-idle", "label": "Uneven idle or shaking at a stop", "componentIds": [ "fuel-air-intake-manifold", "engine-pcv", "fuel-air-injectors", "ignition-ignition-coils", "engine-valves" ], "urgency": "soon", "guidance": "Arrange a misfire and air-leak assessment. Ignition, fueling and poor cylinder sealing can feel alike. Severe shaking with a flashing light is urgent.", "sourceIds": [ "pt-manifold", "pt-injector", "pt-coilcheck", "pt-valves" ], "aliases": [ "rough idle", "rough idling", "uneven idle", "shakes at a stop", "shaking at idle", "car shakes at stoplight", "idle surging", "engine sputters at idle" ] }, { "id": "cooling-overheating-warning", "label": "High temperature warning, steam or overheating", "componentIds": [ "cooling-water-pump", "cooling-radiator", "cooling-thermostat", "cooling-fans", "cooling-head-gasket" ], "urgency": "stop", "guidance": "Stop safely, switch off and arrange assistance. Do not open a hot cooling-system cap. A sensor fault is possible, but actual overheating must be ruled out.", "sourceIds": [ "pt-warning", "pt-coolantsafety", "pt-coolantsensor" ], "aliases": [ "overheating", "car overheating", "engine overheats", "running hot", "temperature light", "temperature gauge high", "steam under hood", "high engine temperature" ] }, { "id": "cooling-repeated-coolant-loss", "label": "Coolant level keeps falling", "componentIds": [ "cooling-hoses", "cooling-water-pump", "cooling-expansion-tank", "cooling-radiator", "cooling-head-gasket" ], "urgency": "soon", "guidance": "Have the cold system tested for external and internal leaks. Stop for rapid loss, steam or rising temperature; repeated topping up does not solve the cause.", "sourceIds": [ "pt-hoses", "pt-waterpump", "pt-cap", "pt-headgasket", "pt-coolantsafety" ], "aliases": [ "coolant leaking", "coolant leak", "leaking coolant", "antifreeze leak", "losing coolant", "coolant level low", "coolant keeps dropping", "puddle of coolant" ] }, { "id": "transmission-revs-without-speed", "label": "Revs rise without matching road speed", "componentIds": [ "transmission-manual-clutch", "transmission-clutch-packs", "transmission-pump", "transmission-valve-body" ], "urgency": "soon", "guidance": "Avoid heavy loads and arrange transmission or clutch diagnosis. Stop and request assistance if propulsion is unreliable or the transmission overheats.", "sourceIds": [ "pt-clutch", "pt-clutchpacks", "pt-transpump" ], "aliases": [ "transmission slips", "transmission slipping", "trans slips", "slipping transmission", "clutch slipping", "engine revs but car won't accelerate", "revs without acceleration", "rpm rises but speed doesn't", "trans slips/shifts hard" ] }, { "id": "transmission-harsh-shifts", "label": "Harsh, delayed or inconsistent shifts", "componentIds": [ "transmission-valve-body", "transmission-solenoids", "transmission-speed-sensors", "transmission-pump" ], "urgency": "soon", "guidance": "Have fluid condition, control signals and hydraulic operation checked. A hard shift does not automatically mean the complete gearbox needs replacement.", "sourceIds": [ "pt-valvebody", "pt-transdiagnosis", "pt-transspeed" ], "aliases": [ "shifts hard", "transmission shifts hard", "hard shifts", "harsh shifting", "rough shifting", "delayed shifting", "jerks when shifting", "trans slips/shifts hard" ] }, { "id": "transmission-light-throttle-shudder", "label": "Shudder during steady, light-throttle cruising", "componentIds": [ "transmission-torque-converter", "transmission-valve-body", "ignition-spark-plugs", "ignition-ignition-coils" ], "urgency": "soon", "guidance": "Ask for a comparison of converter lockup behavior and engine misfire data. Similar vibration can come from either system.", "sourceIds": [ "pt-lockup", "pt-coilcheck" ], "aliases": [ "shudder while cruising", "light throttle shudder", "torque converter shudder", "vibrates at steady speed", "rumble strip feeling", "shakes while driving" ] }, { "id": "cooling-persistent-white-exhaust", "label": "White exhaust persists after warm-up with coolant loss", "componentIds": [ "cooling-head-gasket", "fuel-air-intake-manifold" ], "urgency": "soon", "guidance": "Arrange cooling-system and cylinder-sealing tests. Brief cold-start condensation is different. Stop if overheating, severe misfire or rapid coolant loss develops.", "sourceIds": [ "pt-headgasket", "pt-headcrack", "pt-manifold" ], "aliases": [ "white smoke", "white exhaust", "white smoke after warm up", "white exhaust and coolant loss", "smoke from tailpipe", "white smoke from exhaust" ] }, { "id": "transmission-hard-manual-selection", "label": "Manual gears are hard to select with clutch down", "componentIds": [ "transmission-clutch-release", "transmission-manual-clutch", "transmission-flywheel" ], "urgency": "soon", "guidance": "Have clutch release travel and related bearings checked. Avoid forcing shifts. Stop if gears cannot be selected safely or the car will not disengage drive.", "sourceIds": [ "pt-release" ], "aliases": [ "hard to select gears", "manual won't go into gear", "clutch won't disengage", "clutch pedal down can't shift", "gears hard to engage", "manual transmission hard shifting" ] }, { "id": "brakes-squeal", "label": "Squealing during braking", "componentIds": [ "brakes-pads", "brakes-rotors", "brakes-slide-pins" ], "urgency": "soon", "guidance": "Arrange a brake inspection. A squeal can come from wear, surface condition or hardware. Grinding, reduced braking or smoke raises this to stop safely and seek assistance.", "sourceIds": [ "ch-pads", "ch-brake-noise" ], "aliases": [ "brakes squeal", "squealing brakes", "brakes squeak", "squeaky brakes", "squeak when braking", "high pitched brake noise" ] }, { "id": "brakes-soft-pedal", "label": "Soft or sinking brake pedal", "componentIds": [ "brakes-master-cylinder", "brakes-lines", "brakes-hoses", "brakes-fluid", "brakes-abs-unit" ], "urgency": "stop", "guidance": "Stop safely and arrange assistance. A new low or sinking pedal needs a hydraulic-system diagnosis; pumping or topping up fluid is not proof that the car is safe.", "sourceIds": [ "ch-master", "ch-fluid" ], "aliases": [ "soft brake pedal", "spongy brakes", "brake pedal sinks", "pedal goes to floor", "brakes feel soft", "low brake pedal" ] }, { "id": "brakes-hard-pedal", "label": "Brake pedal suddenly hard to press", "componentIds": [ "brakes-booster", "brakes-vacuum-pump" ], "urgency": "stop", "guidance": "A sudden increase in braking effort can indicate lost assistance. Stop safely and have the assist system checked.", "sourceIds": [ "ch-booster", "ch-vacuum" ], "aliases": [ "hard brake pedal", "brake pedal hard to push", "stiff brake pedal", "heavy brake pedal", "lost brake assist", "brakes need more effort" ] }, { "id": "brakes-hot-wheel", "label": "Hot brake smell or smoke near a wheel", "componentIds": [ "brakes-calipers", "brakes-hoses", "brakes-parking-brake", "brakes-pads" ], "urgency": "stop", "guidance": "Stop safely and arrange help if smoke, strong burning smell or brake drag is present. Avoid touching the wheel or brake. A cooling period does not identify or resolve the fault.", "sourceIds": [ "ch-fluid", "ch-caliper-check", "ch-parking" ], "aliases": [ "hot wheel", "burning smell near wheel", "brake burning smell", "smoking brakes", "smoke from wheel", "brake dragging", "wheel smells hot" ] }, { "id": "brakes-abs-warning", "label": "ABS or stability warning stays on", "componentIds": [ "brakes-wheel-speed-sensors", "brakes-abs-unit", "steering-torque-angle-sensor" ], "urgency": "soon", "guidance": "Have the system checked promptly and consult the vehicle manual. Assistance may be unavailable. A warning plus a changed brake pedal, leakage or reduced braking means stop safely.", "sourceIds": [ "ch-abs", "ch-speed-sensors" ], "aliases": [ "abs light", "abs warning", "abs fault", "stability warning", "traction control light", "stability control light", "abs and traction lights" ] }, { "id": "steering-heavy", "label": "Steering suddenly heavy or unpredictable", "componentIds": [ "steering-eps", "steering-rack", "steering-column-joints", "steering-hydraulic-pump", "steering-torque-angle-sensor" ], "urgency": "stop", "guidance": "Stop safely for sudden binding, unwanted movement or major effort changes. Both electrical-assist faults and mechanical binding need professional assessment.", "sourceIds": [ "ch-eps", "ch-steering-column" ], "aliases": [ "heavy steering", "steering suddenly heavy", "hard to steer", "steering wheel hard to turn", "power steering stopped", "steering binds", "eps warning", "eps light" ] }, { "id": "steering-wandering", "label": "Car wanders or steering feels loose", "componentIds": [ "steering-inner-tie-rods", "steering-outer-tie-rods", "steering-rack-mounts", "suspension-arm-bushings", "wheels-tires" ], "urgency": "soon", "guidance": "Check this promptly. Tire pressure, alignment and mechanical play can overlap. If the car cannot hold a predictable direction, stop and arrange recovery.", "sourceIds": [ "ch-inner-tie", "ch-outer-tie", "ch-steering-diagnosis" ], "aliases": [ "loose steering", "wandering steering", "car wanders", "steering play", "steering feels loose", "steering needs constant correction" ] }, { "id": "suspension-bump-clunk", "label": "Clunk or rattle over bumps", "componentIds": [ "suspension-sway-links", "suspension-strut-mounts", "suspension-ball-joints", "suspension-arm-bushings" ], "urgency": "soon", "guidance": "A technician should locate the moving joint or mounting point. The sound alone cannot distinguish a minor rattle from a joint that affects wheel control.", "sourceIds": [ "ch-sway-links", "ch-strut-mounts", "ch-ball-joints" ], "aliases": [ "clunk over bumps", "clunks over bumps", "rattle over bumps", "knock over bumps", "suspension clunk", "front end clunk", "rattles on rough roads" ] }, { "id": "suspension-bouncing", "label": "Repeated bouncing or floating after bumps", "componentIds": [ "suspension-dampers", "suspension-springs", "wheels-tires" ], "urgency": "soon", "guidance": "Have ride control, tire condition and loading checked. Increasing bounce can reduce grip on rough roads; stop if handling becomes unstable.", "sourceIds": [ "ch-shocks", "ch-springs" ], "aliases": [ "car keeps bouncing", "bouncy ride", "floating over bumps", "bounces after bumps", "car feels floaty", "poor ride control" ] }, { "id": "wheels-speed-vibration", "label": "Vibration at a particular road speed", "componentIds": [ "wheels-balance-weights", "wheels-tires", "wheels-rims", "wheels-fasteners", "axles-propshaft" ], "urgency": "soon", "guidance": "Inspect tires and wheel attachment before assuming balancing will fix it. Sudden severe shaking, wobble or a damaged tire means stop safely.", "sourceIds": [ "ch-wheel-vibration", "ch-bearings", "ch-u-joints" ], "aliases": [ "shakes while driving", "car shakes while driving", "vibration while driving", "highway vibration", "steering wheel shakes at speed", "car shakes at highway speed", "wheel wobble", "vibrates at certain speeds" ] }, { "id": "wheels-pressure-loss", "label": "Tire repeatedly loses air", "componentIds": [ "wheels-tires", "wheels-valves", "wheels-rims", "wheels-tpms" ], "urgency": "soon", "guidance": "Verify pressure against the vehicle placard and arrange a leak inspection. Do not keep driving on a visibly low, flat or rapidly deflating tire.", "sourceIds": [ "ch-tire-care", "ch-rim-leaks", "ch-tpms" ], "aliases": [ "tire losing air", "tyre losing air", "slow puncture", "slow tire leak", "tire pressure keeps dropping", "low tire pressure", "tire keeps going flat" ] }, { "id": "wheels-bulge", "label": "Tire bubble, exposed cords or severe cut", "componentIds": [ "wheels-tires", "wheels-rims" ], "urgency": "stop", "guidance": "Stop safely and arrange roadside assistance. A sidewall bulge can indicate broken internal structure even if the tire still holds air.", "sourceIds": [ "ch-sidewalls", "ch-tires" ], "aliases": [ "tire bulge", "tyre bulge", "bubble in tire", "sidewall bubble", "tire cords showing", "damaged tire sidewall", "severe tire cut" ] }, { "id": "wheels-humming", "label": "Hum or growl rises with road speed", "componentIds": [ "wheels-bearing", "wheels-tires", "axles-differential", "axles-center-support" ], "urgency": "soon", "guidance": "Note whether it changes with road surface, gentle turning or accelerator load and tell the technician. These clues guide inspection but do not prove which part or side is faulty.", "sourceIds": [ "ch-bearings", "ch-differential" ], "aliases": [ "humming", "growling", "humming while driving", "growling while driving", "humming changes with speed", "growling changes with road speed", "humming/growling changes road speed", "wheel bearing noise", "road speed hum" ] }, { "id": "axles-turn-click", "label": "Repeated clicking during powered turns", "componentIds": [ "axles-outer-cv-joints", "axles-cv-boots", "wheels-bearing", "steering-outer-tie-rods" ], "urgency": "soon", "guidance": "Arrange inspection of joints, boots and the wheel end. Stop for heavy knocking, binding or severe vibration; do not repeatedly provoke the noise.", "sourceIds": [ "ch-cv-inspection", "ch-bearings" ], "aliases": [ "clicking when turning", "clicks on turns", "clicking around corners", "cv joint clicking", "clicking on full lock", "clicks when accelerating around a corner" ] }, { "id": "axles-load-shudder", "label": "Shudder or clunk when drive load changes", "componentIds": [ "axles-inner-cv-joints", "axles-halfshafts", "axles-propshaft-joints", "axles-center-support", "axles-differential" ], "urgency": "soon", "guidance": "Ask for a driveline inspection that also considers mounts and wheel faults. Strong underfloor banging, binding or loss of drive means stop safely and arrange assistance.", "sourceIds": [ "ch-cv-noise", "ch-u-joints", "ch-center-bearing", "ch-differential" ], "aliases": [ "shudders accelerating", "shakes under acceleration", "clunk when accelerating", "clunk on throttle", "vibration under load", "driveline clunk", "shakes while driving" ] }, { "id": "starting-slow-crank", "label": "The engine turns over slowly", "componentIds": [ "starting-battery", "starting-cables", "starting-grounds", "starting-starter" ], "urgency": "soon", "guidance": "Have the battery and cranking circuit tested together. Slow cranking does not identify the battery or starter alone.", "sourceIds": [ "el-starter", "el-battery" ], "aliases": [ "slow crank", "cranks slowly", "engine turns slowly", "slow starting", "weak cranking", "barely turns over", "car won't start", "car wont start" ] }, { "id": "starting-silent-no-crank", "label": "No response to the start request", "componentIds": [ "starting-control-circuit", "starting-fuses", "starting-relay", "electrical-can" ], "urgency": "soon", "guidance": "Follow the owner's normal starting instructions and arrange help if the vehicle will not crank. Do not bypass interlocks.", "sourceIds": [ "el-start-tests", "el-can" ], "aliases": [ "car won't start", "car wont start", "won't crank", "wont crank", "no crank", "silent when starting", "nothing when turning key", "start button does nothing", "no response when starting" ] }, { "id": "starting-charge-warning", "label": "Battery or charging light while driving", "componentIds": [ "starting-alternator", "starting-belt-tensioner", "starting-cables", "starting-fuses" ], "urgency": "stop", "guidance": "Move to a safe place and arrange assistance. Charging loss can lead to stalling; a shared belt may also affect cooling on some cars.", "sourceIds": [ "el-alternator", "el-belt", "el-tensioner" ], "aliases": [ "battery light", "battery warning light", "charging light", "charging warning", "alternator warning", "battery symbol while driving" ] }, { "id": "starting-belt-noise", "label": "Squealing or chirping under the hood", "componentIds": [ "starting-belt-tensioner", "starting-alternator", "hvac-compressor" ], "urgency": "soon", "guidance": "Have the accessory drive inspected. Stop if accompanied by charging, overheating or serious steering symptoms.", "sourceIds": [ "el-tensioner", "el-belt" ], "aliases": [ "squealing under hood", "squealing under the hood", "belt squeal", "chirping under hood", "squeaky belt", "squeals on startup", "serpentine belt noise" ] }, { "id": "exhaust-cabin-fumes", "label": "Exhaust fumes inside the cabin", "componentIds": [ "exhaust-pipes", "exhaust-flex-joint", "exhaust-muffler" ], "urgency": "stop", "guidance": "Stop safely, switch off and move into fresh air away from traffic. Arrange recovery; opening a window does not establish safety.", "sourceIds": [ "el-leaks", "el-muffler" ], "aliases": [ "exhaust smell inside", "fumes in cabin", "exhaust fumes in car", "smell exhaust in car", "exhaust odor inside", "cabin fumes" ] }, { "id": "exhaust-new-roar", "label": "New exhaust roar, hiss or rattle", "componentIds": [ "exhaust-pipes", "exhaust-muffler", "exhaust-hangers", "exhaust-flex-joint" ], "urgency": "soon", "guidance": "Arrange an exhaust inspection. Stop if parts are dragging or fumes enter the cabin.", "sourceIds": [ "el-exhaust-inspection", "el-muffler", "el-hangers" ], "aliases": [ "loud exhaust", "exhaust louder", "exhaust roar", "exhaust rumble", "hissing exhaust", "rattling exhaust", "exhaust noise" ] }, { "id": "hvac-warm-air", "label": "A/C blows warm air", "componentIds": [ "hvac-refrigerant-circuit", "hvac-compressor", "hvac-condenser", "hvac-expansion-device", "hvac-blend-door" ], "urgency": "soon", "guidance": "Have cooling performance, charge, airflow and controls checked. Warm air alone does not prove the compressor failed.", "sourceIds": [ "el-ac-service", "el-air-doors" ], "aliases": [ "AC not cold", "ac not cooling", "a/c not cold", "air conditioning not cold", "air conditioner blows warm", "aircon warm", "ac blows hot", "air conditioning stopped working" ] }, { "id": "hvac-weak-airflow", "label": "Weak airflow or missing fan speeds", "componentIds": [ "hvac-cabin-filter", "hvac-blower", "hvac-blend-door" ], "urgency": "soon", "guidance": "Have the filter, blower and air doors checked. Stop driving if the windshield cannot be cleared.", "sourceIds": [ "el-cabin-filter", "el-blower-control", "el-air-doors" ], "aliases": [ "weak airflow", "weak air from vents", "blower not working", "fan speeds missing", "no air from vents", "heater fan not working", "ac fan not blowing" ] }, { "id": "hvac-musty-air", "label": "Musty smell when ventilation starts", "componentIds": [ "hvac-evaporator", "hvac-cabin-filter" ], "urgency": "inspect", "guidance": "Arrange an air-path and moisture inspection. Fuel or exhaust odor calls for stopping, not a cabin-filter assumption.", "sourceIds": [ "el-evaporator", "el-cabin-filter" ], "aliases": [ "musty smell", "musty air conditioning", "moldy ac smell", "mouldy aircon smell", "damp smell from vents", "ventilation smells bad" ] }, { "id": "electrical-many-faults", "label": "Several electrical features fail together", "componentIds": [ "electrical-wiring-harness", "electrical-connectors", "electrical-bcm", "electrical-can", "electrical-fuse-box", "starting-grounds" ], "urgency": "soon", "guidance": "Have shared supplies, grounds and communication checked before replacing modules. Stop for smoke, burning odor or loss of essential control.", "sourceIds": [ "el-ground", "el-voltage-drop", "el-can" ], "aliases": [ "multiple electrical faults", "several warning lights", "electrical problems together", "intermittent electrics", "lights and accessories fail", "many electrical features fail" ] }, { "id": "body-safety-restraint-warning", "label": "Airbag or SRS warning stays on", "componentIds": [ "body-safety-airbags", "body-safety-srs-module", "body-safety-impact-sensors", "body-safety-seat-belts" ], "urgency": "soon", "guidance": "Arrange immediate professional assessment and follow the owner's manual. Do not test restraint connectors yourself. Deployed airbags require repair before driving.", "sourceIds": [ "el-srs", "el-airbags" ], "aliases": [ "airbag light", "srs light", "airbag warning", "restraint warning", "srs warning", "air bag light" ] }, { "id": "body-safety-unsecured", "label": "Door will not latch or seat belt will not secure", "componentIds": [ "body-safety-door-latch", "body-safety-seat-belts" ], "urgency": "stop", "guidance": "Do not drive with an unsecured door. Do not occupy a seat with an unusable belt. Arrange repair before the affected vehicle or seat is used.", "sourceIds": [ "el-latch", "el-seat-belts" ], "aliases": [ "door won't latch", "door wont latch", "door won't close", "seat belt won't latch", "seatbelt won't buckle", "belt won't secure", "unsecured door" ] }, { "id": "body-safety-poor-visibility", "label": "Wipers or defogging cannot keep the windshield clear", "componentIds": [ "body-safety-wiper-blades", "electrical-wiper-motor", "hvac-blower", "hvac-blend-door", "hvac-cabin-filter" ], "urgency": "stop", "guidance": "Pull over safely and wait or arrange assistance. Continue only when a clear view can be maintained.", "sourceIds": [ "el-wipers", "el-air-doors", "el-cabin-filter" ], "aliases": [ "windshield won't clear", "windshield fogging", "windscreen won't clear", "can't defog windshield", "wipers not clearing", "can't see in rain", "poor visibility" ] }, { "id": "starting-click-no-crank", "label": "Clicking when starting, but the engine will not turn", "componentIds": [ "starting-battery", "starting-cables", "starting-grounds", "starting-solenoid", "starting-starter", "starting-relay", "starting-control-circuit" ], "urgency": "soon", "guidance": "Stop repeated attempts and arrange starting-system testing. Battery condition, both cable paths, control voltage and the starter all matter. A single click or rapid clicking is a clue, not proof of one failed part. If the engine is actually turning, use the cranks-but-will-not-start entry instead.", "sourceIds": [ "el-start-tests", "el-starter", "el-battery" ], "aliases": [ "clicking when starting", "clicks but won't start", "rapid clicking", "single click no start", "clicking no crank", "starter clicks", "car won't start", "car wont start", "no start" ] }, { "id": "brakes-pulsation", "label": "Steering wheel shakes or pedal pulses when braking", "componentIds": [ "brakes-rotors", "brakes-calipers", "wheels-hub", "wheels-bearing", "suspension-arm-bushings", "suspension-control-arms", "brakes-wheel-speed-sensors" ], "urgency": "soon", "guidance": "Arrange inspection of disc condition and mounting, caliper movement, wheel-bearing play and suspension joints. Normal ABS intervention can briefly pulse the pedal, but repeated shaking during ordinary stops needs diagnosis. Stop safely for severe vibration, unpredictable steering or reduced braking.", "sourceIds": [ "ch-rotors", "ch-brake-noise", "ch-bearings", "ch-control-arms", "ch-abs", "qa-disc-damage" ], "aliases": [ "steering wheel shakes when braking", "steering shakes when braking", "car shakes when braking", "brake pedal pulsates", "brakes pulsate", "brake vibration", "brake judder", "shudder under braking" ] }, { "id": "steering-pulls-one-side", "label": "Car pulls to one side", "componentIds": [ "wheels-tires", "brakes-calipers", "brakes-hoses", "brakes-slide-pins", "suspension-arm-bushings", "suspension-control-arms", "steering-outer-tie-rods", "wheels-bearing" ], "urgency": "soon", "guidance": "Tell the technician whether the pull is constant, follows a tire change or appears mainly when braking. Tire condition, alignment, steering or suspension play, and unequal braking need separate checks. Do not assume alignment alone will fix it. Stop safely if the pull is sudden, strong or makes direction unpredictable.", "sourceIds": [ "ch-steering-diagnosis", "ch-control-arms", "ch-outer-tie", "ch-caliper-check", "ch-slide-pins", "ch-bearings" ], "aliases": [ "pulls one side", "pulls to one side", "car pulls left", "car pulls right", "pulls when braking", "pulls under braking", "car pulling", "drifts to one side" ] }, { "id": "brakes-grinding", "label": "Grinding or harsh scraping when braking", "componentIds": [ "brakes-pads", "brakes-rotors", "brakes-calipers", "brakes-slide-pins", "wheels-bearing" ], "urgency": "stop", "guidance": "For a new persistent or harsh grinding sound, stop safely and arrange a brake and wheel-end inspection before continuing. Possible explanations include severe friction-material wear, damaged brake parts or a wheel-end problem. Sound alone cannot establish the cause or remaining braking ability.", "sourceIds": [ "qa-disc-damage", "ch-pads", "ch-slide-pins", "ch-bearings" ], "aliases": [ "brakes grind", "brakes grinding", "grinding brakes", "grinding when braking", "scraping when braking", "metallic brake scrape", "harsh brake grinding" ] }, { "id": "engine-ticking", "label": "Ticking from the engine while it is running", "componentIds": [ "fuel-air-high-pressure-pump", "fuel-air-injectors", "engine-oil-pump", "engine-oil-filter", "engine-valves" ], "urgency": "soon", "guidance": "Have a new, louder or persistent tick assessed rather than replacing parts from the sound alone. Some direct-injection pumps and injectors make normal ticking on specific engines. A technician can distinguish these from valve-train or lubrication concerns. Stop safely and switch off for an oil-pressure warning, heavy knocking or severe rough running.", "sourceIds": [ "qa-gdi-ticking", "qa-lubrication-ticking", "pt-warning", "pt-valves" ], "aliases": [ "engine ticking", "ticking engine", "tick from engine", "ticking under hood", "ticking while running", "engine taps", "tapping engine" ] }, { "id": "electrical-burning-smell", "label": "Burning smell or unexplained smoke", "componentIds": [ "electrical-wiring-harness", "electrical-connectors", "starting-belt-tensioner", "brakes-calipers", "brakes-parking-brake", "transmission-manual-clutch" ], "urgency": "stop", "guidance": "Stop safely and switch off for a strong unexplained burning smell or smoke. Heat may involve brakes, a clutch, an accessory drive or electrical parts; odor cannot identify the cause. If fire is suspected, get everyone clear of traffic and the vehicle, keep the hood closed, and call emergency services. Do not continue just because the smell fades.", "sourceIds": [ "qa-vehicle-fire", "ch-fluid", "ch-caliper-check", "pt-clutch", "el-tensioner", "el-voltage-drop" ], "aliases": [ "burning smell", "smells like burning", "burning odor", "burning plastic smell", "smoke under hood", "unexplained smoke", "hot electrical smell" ] }, { "id": "engine-oil-leak", "label": "Oil leak or oily puddle under the car", "componentIds": [ "engine-oil-filter", "engine-pcv", "transmission-cooler", "axles-shaft-seals", "steering-hydraulic-hoses" ], "urgency": "soon", "guidance": "Arrange a leak inspection that identifies the fluid and traces its source. Oil can travel before it drips, and color or parking position alone is not enough. Engine gaskets and seals beyond this component list can also leak. Stop safely for rapid loss, an oil-pressure warning, smoke, fuel odor or a change in braking or steering.", "sourceIds": [ "pt-leaks", "pt-filters", "pt-pcv", "pt-transcooler", "ch-axle-seals", "ch-hydraulic-steering", "pt-warning" ], "aliases": [ "oil leaking", "oil leak", "leaking oil", "oil puddle", "oily puddle", "oil spots under car", "dripping oil" ] }, { "id": "fuel-air-raw-fuel-odor", "label": "Fuel smell or visible gasoline", "componentIds": [ "fuel-air-fuel-pump", "fuel-air-high-pressure-pump", "fuel-air-injectors", "fuel-air-fuel-filter", "exhaust-charcoal-canister", "exhaust-purge-valve", "exhaust-vent-valve" ], "urgency": "stop", "guidance": "Stop safely, switch off and arrange assistance if gasoline smell persists or fuel is visible. Keep away from flames and sparks, and do not restart to test it. Fuel lines, seals and vapor-system faults need inspection; an EVAP code does not rule out a liquid-fuel leak.", "sourceIds": [ "pt-fuelleaksafety", "pt-leaks", "el-charcoal", "el-evap" ], "aliases": [ "fuel smell", "gasoline smell", "petrol smell", "gas smell", "smells like gas", "fuel leaking", "gasoline leak", "visible fuel" ] }, { "id": "cooling-weak-cabin-heat", "label": "Heat not working or cabin air stays cold", "componentIds": [ "cooling-thermostat", "cooling-heater-core", "cooling-water-pump", "cooling-hoses", "hvac-blend-door", "hvac-blower" ], "urgency": "soon", "guidance": "A technician should separate weak airflow from air that flows normally but stays cold. Coolant temperature and circulation, heater-core flow, and air-door control all matter. Stop safely for overheating or if the windshield cannot be kept clear. Never open a hot coolant system.", "sourceIds": [ "pt-thermostat", "pt-heater", "pt-coolingchecks", "pt-coolantsafety", "el-air-doors", "el-blower-control" ], "aliases": [ "heat not working", "heater not working", "no cabin heat", "heater blows cold", "car heater cold", "heat stays cold", "cold air from heater" ] }, { "id": "exhaust-steady-engine-light", "label": "Check-engine light stays on", "componentIds": [ "exhaust-oxygen-sensors", "exhaust-catalyst", "exhaust-purge-valve", "exhaust-vent-valve", "fuel-air-maf-sensor", "fuel-air-injectors", "ignition-ignition-coils", "ignition-throttle-body" ], "urgency": "soon", "guidance": "Arrange a diagnostic scan and testing of the reported condition. Ignition, fuel, air, sensor, wiring and emissions faults can overlap, and a fault code is not a parts-shopping list. A flashing light with shaking, major power loss, overheating or oil-pressure warning calls for stopping safely.", "sourceIds": [ "el-catalyst", "el-oxygen-tests", "el-evap", "pt-maf", "pt-injector", "pt-coilcheck", "pt-tps", "pt-misfire", "pt-warning" ], "aliases": [ "check engine light", "check-engine light", "engine warning light", "engine management light", "cel light", "service engine soon", "engine light stays on" ] } ] }