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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.

Check soon P · Powertrain Clear all

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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 3241–3264 of 6682

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P20A9Reductant Injection Air Pressure Control Valve Circuit HighCheck soonFuel System30–120 minutes for initial diagnosisP20A9 relates to reductant injection air pressure control valve circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20AAReductant Injection Air Pressure Control Valve Stuck OpenCheck soonFuel System30–120 minutes for initial diagnosisP20AA relates to reductant injection air pressure control valve stuck open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20ABReductant Injection Air Pressure Control Valve Stuck ClosedCheck soonFuel System30–120 minutes for initial diagnosisP20AB relates to reductant injection air pressure control valve stuck closed. Check the fault conditions and vehicle-specific procedure before replacing parts.P20ACReductant Metering Unit Temperature Sensor CircuitCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20AC relates to reductant metering unit temperature sensor circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P20ADReductant Metering Unit Temperature Sensor Circuit Range/PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20AD relates to reductant metering unit temperature sensor circuit range/performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P20AEReductant Metering Unit Temperature Sensor Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20AE relates to reductant metering unit temperature sensor circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20AFReductant Metering Unit Temperature Sensor Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20AF relates to reductant metering unit temperature sensor circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B0Reductant Metering Unit Temperature Sensor Circuit Intermittent/ErraticCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20B0 relates to reductant metering unit temperature sensor circuit intermittent/erratic. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B1Reductant Heater Coolant Control Valve Circuit/OpenCheck soonEngine Problems30–120 minutes for initial diagnosisP20B1 relates to reductant heater coolant control valve circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B2Reductant Heater Coolant Control Valve Performance/Stuck OpenCheck soonEngine Problems30–120 minutes for initial diagnosisP20B2 relates to reductant heater coolant control valve performance/stuck open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B3Reductant Heater Coolant Control Valve Circuit LowCheck soonEngine Problems30–120 minutes for initial diagnosisP20B3 relates to reductant heater coolant control valve circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B4Reductant Heater Coolant Control Valve Circuit HighCheck soonEngine Problems30–120 minutes for initial diagnosisP20B4 relates to reductant heater coolant control valve circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B5Reductant Metering Unit Heater Control Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20B5 relates to reductant metering unit heater control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B6Reductant Metering Unit Heater Control Circuit PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20B6 relates to reductant metering unit heater control circuit performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B7Reductant Metering Unit Heater Control Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20B7 relates to reductant metering unit heater control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B8Reductant Metering Unit Heater Control Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20B8 relates to reductant metering unit heater control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20B9Reductant Heater A Control Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20B9 relates to reductant heater a control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20BAReductant Heater A Control Circuit PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20BA relates to reductant heater a control circuit performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P20BBReductant Heater A Control Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20BB relates to reductant heater a control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20BCReductant Heater A Control Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20BC relates to reductant heater a control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20BDReductant Heater B Control Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20BD relates to reductant heater b control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20BEReductant Heater B Control Circuit PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20BE relates to reductant heater b control circuit performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P20BFReductant Heater B Control Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20BF relates to reductant heater b control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C0Reductant Heater B Control Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C0 relates to reductant heater b control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.