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.
- 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
- P0430Audi · PowertrainDefective Catalytic Converter, Internal engine damage resulting in high oil consumption and or a leaking Head Gasket has damaged the Catalytic Converter
- 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
- P043CGeneric · PowertrainCatalyst Temperature Sensor Circuit Low Bank 2 Sensor 2
- P043DGeneric · PowertrainCatalyst Temperature Sensor Circuit High Bank 2 Sensor 2
- P043EGeneric · PowertrainEVAP System Leak Detection Reference Orifice Low Flow
- P043FGeneric · PowertrainEVAP System Leak Detection Reference Orifice High Flow
- P0440Generic · PowertrainEVAP System
- P0440Audi · PowertrainMissing fuel cap, Defective or damaged fuel cap, Distorted or damaged Fuel Tank Filler Neck, Torn or punctured Evaporative system hose(s), Defective Fuel Tank Sending Unit gasket or seal, Split or damaged Carbon Canister, Defective Evaporative Vent Valve and or Evaporative Purge Valve, Defective or damaged fuel tank
- P0441Generic · PowertrainEVAP System Incorrect Purge Flow
- P0441Audi · PowertrainMissing fuel cap, Stuck open or closed purge valve, Defective or damaged fuel cap, Distorted damaged or cracked Fuel Tank Filler Neck, Torn or punctured Evaporative system hose(s), Defective Fuel Tank Sending Unit gasket or seal, Split or damaged Carbon Canister, Defective Evaporative Vent Valve, Defective or damaged fuel tank
- P0442Generic · PowertrainEVAP System Leak Detected (small leak)
- P0442Audi · PowertrainDefective or damaged fuel cap, Distorted or damaged Fuel Tank Filler Neck, Small tear or puncture in the Evaporative system hose(s) and or Carbon Canister, Defective Fuel Tank Sending Unit gasket or seal, Small split in a seam of the Carbon Canister, Defective Evaporative Vent Valve and or Evaporative Purge Valve, Defective or damaged Fuel Tank, Defective Fuel Tank Pressure Sensor, Defective Leak Detection Pump, Slightly loose and or worn clamps or hardened O-rings anywhere in the EVAP system
- P0442Dodge · PowertrainMedium EVAP Leak
