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9,253 diagnostic guides

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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 937–960 of 1939

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P21AAReductant Level Sensor B Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21AA relates to reductant level sensor b circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P21ABReductant Level Sensor B Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21AB relates to reductant level sensor b circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P21ACReductant Level Sensor B Circuit Intermittent/ErraticCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21AC relates to reductant level sensor b circuit intermittent/erratic. Check the fault conditions and vehicle-specific procedure before replacing parts.P21ADReductant Level Sensor C CircuitCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21AD relates to reductant level sensor c circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P21AEReductant Level Sensor C Circuit Range/PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21AE relates to reductant level sensor c circuit range/performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P21AFReductant Level Sensor C Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21AF relates to reductant level sensor c circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P21B0Reductant Level Sensor C Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21B0 relates to reductant level sensor c circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P21B1Reductant Level Sensor C Circuit Intermittent/ErraticCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21B1 relates to reductant level sensor c circuit intermittent/erratic. Check the fault conditions and vehicle-specific procedure before replacing parts.P21B2Excessive Time To Enter Closed Loop NOx Adsorber ControlCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21B2 relates to excessive time to enter closed loop nox adsorber control. Check the fault conditions and vehicle-specific procedure before replacing parts.P21B3Closed Loop NOx Adsorber Control At Limit - Too HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21B3 relates to closed loop nox adsorber control at limit - too high. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C5Reductant Level Sensor A StuckCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21C5 relates to reductant level sensor a stuck. Check the fault conditions and vehicle-specific procedure before replacing parts.P21C6Reductant Level Sensor B StuckCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21C6 relates to reductant level sensor b stuck. Check the fault conditions and vehicle-specific procedure before replacing parts.P21CEReductant Quality Module PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21CE relates to reductant quality module performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P21DDReductant Heater A Current Too LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP21DD relates to reductant heater a current too low. Check the fault conditions and vehicle-specific procedure before replacing parts.P2200NOx Sensor Circuit Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2200 relates to nox sensor circuit bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2201NOx Sensor Circuit Range/Performance Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2201 relates to nox sensor circuit range/performance bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2202NOx Sensor Circuit Low Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2202 relates to nox sensor circuit low bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2203NOx Sensor Circuit High Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2203 relates to nox sensor circuit high bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2204NOx Sensor Circuit Intermittent Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2204 relates to nox sensor circuit intermittent bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2205NOx Sensor Heater Control Circuit/Open Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2205 relates to nox sensor heater control circuit/open bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2206NOx Sensor Heater Control Circuit Low Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2206 relates to nox sensor heater control circuit low bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2207NOx Sensor Heater Control Circuit High Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2207 relates to nox sensor heater control circuit high bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2208NOx Sensor Heater Sense Circuit Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2208 relates to nox sensor heater sense circuit bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P2209NOx Sensor Heater Sense Circuit Range/Performance Bank 1 Sensor 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP2209 relates to nox sensor heater sense circuit range/performance bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.