DTC codes
Look up an OBD-II fault code: what it means on every car or on your make, and how to track it down.
How to read a code
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 4
- AreaAuxiliary emission controls
- 20
- FaultThe specific fault in that area
Read the code
Note every stored and pending code your scanner shows, such as P0420.
Find it
Search by code or by words. For a manufacturer code (P1, B1, C1, U1) pick your make: its meaning differs by make.
Open the code
Its page explains the symptoms, likely causes, the checks to run and the fixes.
- P041EGeneric · PowertrainEGR Temperature Sensor B Circuit Intermittent/Erratic
- P041FGeneric · PowertrainAIR System Switching Valve A Circuit Low
- P0420Generic · PowertrainCatalyst System Efficiency Below Threshold Bank 1
- P0421Generic · PowertrainCatalyst 1 Efficiency Below Threshold Bank 1
- P0422Generic · PowertrainCatalyst 2 Efficiency Below Threshold Bank 1
- P0423Generic · PowertrainHeated Catalyst Efficiency Below Threshold Bank 1
- P0424Generic · PowertrainHeated Catalyst Temperature Below Threshold Bank 1
- P0425Generic · PowertrainCatalyst Temperature Sensor Circuit Bank 1 Sensor 1
- P0426Generic · PowertrainCatalyst Temperature Sensor Circuit Range/Performance Bank 1 Sensor 1
- P0427Generic · PowertrainCatalyst Temperature Sensor Circuit Low Bank 1 Sensor 1
- P0428Generic · PowertrainCatalyst Temperature Sensor Circuit High Bank 1 Sensor 1
- P0429Generic · PowertrainCatalyst Heater Control Circuit/Open Bank 1
- P042AGeneric · PowertrainCatalyst Temperature Sensor Circuit Bank 1 Sensor 2
- P042BGeneric · PowertrainCatalyst Temperature Sensor Circuit Range/Performance Bank 1 Sensor 2
- P042CGeneric · PowertrainCatalyst Temperature Sensor Circuit Low Bank 1 Sensor 2
- P042DGeneric · PowertrainCatalyst Temperature Sensor Circuit High Bank 1 Sensor 2
- P042EGeneric · PowertrainEGR A Control Stuck Open
- P042FGeneric · PowertrainEGR A Control Stuck Closed
- P0430Generic · PowertrainCatalyst System Efficiency Below Threshold Bank 2
- P0431Generic · PowertrainCatalyst 1 Efficiency Below Threshold Bank 2
- P0432Generic · PowertrainCatalyst 2 Efficiency Below Threshold Bank 2
- P0433Generic · PowertrainHeated Catalyst Efficiency Below Threshold Bank 2
- P0434Generic · PowertrainHeated Catalyst Temperature Below Threshold Bank 2
- P0435Generic · PowertrainCatalyst Temperature Sensor Circuit Bank 2 Sensor 1
- P0436Generic · PowertrainCatalyst Temperature Sensor Circuit Range/Performance Bank 2 Sensor 1
- P0437Generic · PowertrainCatalyst Temperature Sensor Circuit Low Bank 2 Sensor 1
- P0438Generic · PowertrainCatalyst Temperature Sensor Circuit High Bank 2 Sensor 1
- P0439Generic · PowertrainCatalyst Heater Control Circuit/Open Bank 2
- P043AGeneric · PowertrainCatalyst Temperature Sensor Circuit Bank 2 Sensor 2
- P043BGeneric · PowertrainCatalyst Temperature Sensor Circuit Range/Performance Bank 2 Sensor 2
