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9,253 diagnostic guides

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Find codes by symptomChoose what you notice to search matching code guides.

Rough idle or shakingVibration while stopped Hard to startLong cranking or no-start Engine stallsCuts out at idle or on the road Hesitates or loses powerSlow response when accelerating Battery light is onCharging system warning Harsh gear changesDelayed or rough shifting

A symptom can have several causes. Treat matching codes as clues and follow the diagnostic checks in each guide.

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Engine1049 Emissions515 Fuel1016 Sensors & Electronics2110 Transmission866 Electrical & Charging1797 Body & Restraints193 Chassis & Brakes479 Network & Communication1228

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All severities9253 Low priority305 Check soon8256 Urgent621

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All families9253 P · Powertrain7353 B · Body193 C · Chassis479 U · Network1228

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These are generic OBD2 definitions. Exact make, model, engine, and year compatibility will appear after vehicle-fitment data is added.

Diagnostic codes

Showing 1129–1152 of 7353

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P0504Brake Switch A/B CorrelationCheck soonSensors & Electronics30–90 minutes for initial diagnosisP0504 means the brake-pedal switch signals disagree when the control module expects them to match. Learn what to check before replacing parts.P0505Idle Air Control System MalfunctionEngine ProblemsDiagnose P0505 idle control code. Learn about the IAC valve and how to fix idle speed problems.P0506Idle Control System RPM Lower Than ExpectedCheck soonEngine Problems30–120 minutes for initial diagnosisP0506 indicates a fault related to idle control system rpm lower than expected. Learn the likely causes and a practical diagnostic order before replacing parts.P0507Idle Control System RPM Higher Than ExpectedEngine ProblemsFix P0507 high idle code. Learn why your engine idle speed is too high and how to correct it.P0508Idle Air Control System Circuit LowCheck soonEngine Problems30–120 minutes for initial diagnosisP0508 indicates a fault related to idle air control system circuit low. Learn the likely causes and a practical diagnostic order before replacing parts.P0509Idle Air Control System Circuit HighCheck soonEngine Problems30–120 minutes for initial diagnosisP0509 indicates a fault related to idle air control system circuit high. Learn the likely causes and a practical diagnostic order before replacing parts.P050ACold Start Idle Control System PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP050A relates to cold start idle control system performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P050BCold Start Ignition Timing PerformanceCheck soonEngine Problems30–120 minutes for initial diagnosisP050B relates to cold start ignition timing performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P050CCold Start Engine Coolant Temperature PerformanceCheck soonEngine Problems30–120 minutes for initial diagnosisP050C relates to cold start engine coolant temperature performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P050DCold Start Rough IdleCheck soonSensors & Electronics30–120 minutes for initial diagnosisP050D relates to cold start rough idle. Check the fault conditions and vehicle-specific procedure before replacing parts.P050ECold Start Engine Exhaust Temperature Too LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP050E relates to cold start engine exhaust temperature too low. Check the fault conditions and vehicle-specific procedure before replacing parts.P050FBrake Assist Vacuum Too LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP050F relates to brake assist vacuum too low. Check the fault conditions and vehicle-specific procedure before replacing parts.P0510Closed Throttle Position Switch MalfunctionCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0510 indicates a fault related to closed throttle position switch malfunction. Learn the likely causes and a practical diagnostic order before replacing parts.P0511Idle Air Control CircuitCheck soonEngine Problems30–120 minutes for initial diagnosisP0511 indicates a fault related to idle air control circuit. Learn the likely causes and a practical diagnostic order before replacing parts.P0512Starter Request CircuitCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0512 indicates a fault related to starter request circuit. Learn the likely causes and a practical diagnostic order before replacing parts.P0513Incorrect Immobilizer KeyCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0513 indicates a fault related to incorrect immobilizer key. Learn the likely causes and a practical diagnostic order before replacing parts.P0514Battery Temperature Sensor Circuit Range/PerformanceCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0514 indicates a fault related to battery temperature sensor circuit range/performance. Learn the likely causes and a practical diagnostic order before replacing parts.P0515Battery Temperature Sensor CircuitCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0515 indicates a fault related to battery temperature sensor circuit. Learn the likely causes and a practical diagnostic order before replacing parts.P0516Battery Temperature Sensor Circuit LowCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0516 indicates a fault related to battery temperature sensor circuit low. Learn the likely causes and a practical diagnostic order before replacing parts.P0517Battery Temperature Sensor Circuit HighCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0517 indicates a fault related to battery temperature sensor circuit high. Learn the likely causes and a practical diagnostic order before replacing parts.P0518Idle Air Control Circuit IntermittentCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0518 relates to idle air control circuit intermittent. Check the fault conditions and vehicle-specific procedure before replacing parts.P0519Idle Air Control System PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0519 relates to idle air control system performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P051ACrankcase Pressure Sensor A CircuitCheck soonSensors & Electronics30–120 minutes for initial diagnosisP051A relates to crankcase pressure sensor a circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P051BCrankcase Pressure Sensor A Circuit Range/PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP051B relates to crankcase pressure sensor a circuit range/performance. Check the fault conditions and vehicle-specific procedure before replacing parts.