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.
- P1800GM · PowertrainTCM Power Control Relay Circuit Open
- P1800GMC · PowertrainTCM Power Control Relay Circuit Open
- P1800Oldsmobile · PowertrainTCM Power Control Relay Circuit Open
- P1800Other · PowertrainTransmission Clutch Interlock Safety Switch Circuit Failure
- P1800Saturn · PowertrainTCM Power Control Relay Circuit Open
- P1801Buick · PowertrainPerformance Selector Switch Failure
- P1801Cadillac · PowertrainPerformance Selector Switch Failure
- P1801Chevrolet · PowertrainPerformance Selector Switch Failure
- P1801GM · PowertrainPerformance Selector Switch Failure
- P1801GMC · PowertrainPerformance Selector Switch Failure
- P1801Oldsmobile · PowertrainPerformance Selector Switch Failure
- P1801Other · PowertrainTransmission Clutch Interlock Safety Switch Open Circuit
- P1801Saturn · PowertrainPerformance Selector Switch Failure
- P1802Other · PowertrainTransmission Clutch Interlock Safety Switch Short Circuit To Battery
- P1803Other · PowertrainTransmission Clutch Interlock Safety Switch Short Circuit To Ground
- P1804Buick · PowertrainGround Control Relay
- P1804Cadillac · PowertrainGround Control Relay
- P1804Chevrolet · PowertrainGround Control Relay
- P1804Ford · PowertrainTransmission 4-Wheel Drive High Indicator Circuit Failure
- P1804GM · PowertrainGround Control Relay
- P1804GMC · PowertrainGround Control Relay
- P1804Lincoln · PowertrainTransmission 4-Wheel Drive High Indicator Circuit Failure
- P1804Mercury · PowertrainTransmission 4-Wheel Drive High Indicator Circuit Failure
- P1804Oldsmobile · PowertrainGround Control Relay
- P1804Other · PowertrainTransmission 4-Wheel Drive High Indicator Circuit Failure
- P1804Saturn · PowertrainGround Control Relay
- P1805Other · PowertrainTransmission 4-Wheel Drive High Indicator Open Circuit
- P1806Ford · PowertrainTransmission 4-Wheel Drive High Indicator Short Circuit To Battery
- P1806Lincoln · PowertrainTransmission 4-Wheel Drive High Indicator Short Circuit To Battery
- P1806Mercury · PowertrainTransmission 4-Wheel Drive High Indicator Short Circuit To Battery
