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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 817–840 of 1939

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P20C1Reductant Heater C Control Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C1 relates to reductant heater c control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C2Reductant Heater C Control Circuit PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C2 relates to reductant heater c control circuit performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C3Reductant Heater C Control Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C3 relates to reductant heater c control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C4Reductant Heater C Control Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C4 relates to reductant heater c control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C5Reductant Heater D Control Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C5 relates to reductant heater d control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C6Reductant Heater D Control Circuit PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C6 relates to reductant heater d control circuit performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C7Reductant Heater D Control Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C7 relates to reductant heater d control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C8Reductant Heater D Control Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C8 relates to reductant heater d control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20C9Reductant Control Module Requested MIL IlluminationCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20C9 relates to reductant control module requested mil illumination. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E8Reductant Pressure Too LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20E8 relates to reductant pressure too low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E9Reductant Pressure Too HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20E9 relates to reductant pressure too high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20F4Reductant Consumption Too LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20F4 relates to reductant consumption too low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20F5Reductant Consumption Too HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20F5 relates to reductant consumption too high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20F8Intake Manifold Runner Control Circuit Performance Bank 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP20F8 relates to intake manifold runner control circuit performance bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P20F9Intake Manifold Runner Control Circuit Performance Bank 2Check soonSensors & Electronics30–120 minutes for initial diagnosisP20F9 relates to intake manifold runner control circuit performance bank 2. Check the fault conditions and vehicle-specific procedure before replacing parts.P20FAReductant Pump B Control Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20FA relates to reductant pump b control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20FBReductant Pump B Control Performance/Stuck OffCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20FB relates to reductant pump b control performance/stuck off. Check the fault conditions and vehicle-specific procedure before replacing parts.P20FCReductant Pump B Control Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20FC relates to reductant pump b control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20FDReductant Pump B Control Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20FD relates to reductant pump b control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20FEReductant Metering Unit 1 PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20FE relates to reductant metering unit 1 performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P20FFReductant Control Module PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP20FF relates to reductant control module performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P2100Throttle Actuator A Control Motor Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP2100 relates to throttle actuator a control motor circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P2101Throttle Actuator A Control Motor Circuit Range/PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP2101 relates to throttle actuator a control motor circuit range/performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P2102Throttle Actuator A Control Motor Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP2102 relates to throttle actuator a control motor circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.