Diagnostic library

Find an OBD2 code

Search the code from your scanner, then narrow the library by system, severity, or code family.

9,253 diagnostic guides

Sort

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.

P · Powertrain Clear all

Quick browse

Choose a vehicle system

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

FiltersSeverity · family

Severity

All severities9253 Low priority305 Check soon8256 Urgent621

Code family

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

Vehicle coverage

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

Diagnostic codes

Showing 3745–3768 of 7353

Most searched first

P20DBExhaust Aftertreatment Fuel Supply Control Stuck OpenCheck soonFuel System30–120 minutes for initial diagnosisP20DB relates to exhaust aftertreatment fuel supply control stuck open. Check the fault conditions and vehicle-specific procedure before replacing parts.P20DCExhaust Aftertreatment Fuel Supply Control Stuck ClosedCheck soonFuel System30–120 minutes for initial diagnosisP20DC relates to exhaust aftertreatment fuel supply control stuck closed. Check the fault conditions and vehicle-specific procedure before replacing parts.P20DDExhaust Aftertreatment Fuel Pressure Sensor CircuitCheck soonFuel System30–120 minutes for initial diagnosisP20DD relates to exhaust aftertreatment fuel pressure sensor circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P20DEExhaust Aftertreatment Fuel Pressure Sensor Circuit Range/PerformanceCheck soonFuel System30–120 minutes for initial diagnosisP20DE relates to exhaust aftertreatment fuel pressure sensor circuit range/performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P20DFExhaust Aftertreatment Fuel Pressure Sensor Circuit LowCheck soonFuel System30–120 minutes for initial diagnosisP20DF relates to exhaust aftertreatment fuel pressure sensor circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E0Exhaust Aftertreatment Fuel Pressure Sensor Circuit HighCheck soonFuel System30–120 minutes for initial diagnosisP20E0 relates to exhaust aftertreatment fuel pressure sensor circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E1Exhaust Aftertreatment Fuel Pressure Sensor Circuit Intermittent/ErraticCheck soonFuel System30–120 minutes for initial diagnosisP20E1 relates to exhaust aftertreatment fuel pressure sensor circuit intermittent/erratic. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E2Exhaust Gas Temperature Sensor 1/2 Correlation Bank 1Check soonEmissions System30–120 minutes for initial diagnosisP20E2 relates to exhaust gas temperature sensor 1/2 correlation bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E3Exhaust Gas Temperature Sensor 1/3 Correlation Bank 1Check soonEmissions System30–120 minutes for initial diagnosisP20E3 relates to exhaust gas temperature sensor 1/3 correlation bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E4Exhaust Gas Temperature Sensor 2/3 Correlation Bank 1Check soonEmissions System30–120 minutes for initial diagnosisP20E4 relates to exhaust gas temperature sensor 2/3 correlation bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E5Exhaust Gas Temperature Sensor 1/2 Correlation Bank 2Check soonEmissions System30–120 minutes for initial diagnosisP20E5 relates to exhaust gas temperature sensor 1/2 correlation bank 2. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E6Reductant Injection Air Pressure Too LowCheck soonFuel System30–120 minutes for initial diagnosisP20E6 relates to reductant injection air pressure too low. Check the fault conditions and vehicle-specific procedure before replacing parts.P20E7Reductant Injection Air Pressure Too HighCheck soonFuel System30–120 minutes for initial diagnosisP20E7 relates to reductant injection air pressure too high. 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.P20EAReductant Control Module Power Relay De-Energized Performance - Too EarlyCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP20EA relates to reductant control module power relay de-energized performance - too early. Check the fault conditions and vehicle-specific procedure before replacing parts.P20EBReductant Control Module Power Relay De-Energized Performance - Too LateCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP20EB relates to reductant control module power relay de-energized performance - too late. Check the fault conditions and vehicle-specific procedure before replacing parts.P20ECSCR NOx Catalyst - Over Temperature Bank 1UrgentEmissions System30–120 minutes for initial diagnosisP20EC relates to scr nox catalyst - over temperature bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P20EDSCR NOx Pre-Catalyst - Over Temperature Bank 1UrgentEmissions System30–120 minutes for initial diagnosisP20ED relates to scr nox pre-catalyst - over temperature bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P20EESCR NOx Catalyst Efficiency Below Threshold Bank 1 Catalyst 1Low priorityEmissions System30–120 minutes for initial diagnosisP20EE relates to scr nox catalyst efficiency below threshold bank 1 catalyst 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P20EFSCR NOx Pre- Catalyst Efficiency Below Threshold Bank 1Low priorityEmissions System30–120 minutes for initial diagnosisP20EF relates to scr nox pre- catalyst efficiency below threshold bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P20F0SCR NOx Catalyst - Over Temperature Bank 2UrgentEmissions System30–120 minutes for initial diagnosisP20F0 relates to scr nox catalyst - over temperature bank 2. Check the fault conditions and vehicle-specific procedure before replacing parts.P20F1SCR NOx Pre-Catalyst - Over Temperature Bank 2UrgentEmissions System30–120 minutes for initial diagnosisP20F1 relates to scr nox pre-catalyst - over temperature bank 2. Check the fault conditions and vehicle-specific procedure before replacing parts.P20F2SCR NOx Catalyst Efficiency Below Threshold Bank 2Low priorityEmissions System30–120 minutes for initial diagnosisP20F2 relates to scr nox catalyst efficiency below threshold bank 2. Check the fault conditions and vehicle-specific procedure before replacing parts.