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.
- U301DGeneric · NetworkControl Module Wake-up Circuit A Performance
- U301EGeneric · NetworkControl Module Wake-up Circuit B/Open
- U301FGeneric · NetworkControl Module Wake-up Circuit B Low
- U3020Generic · NetworkControl Module Wake-up Circuit B High
- U3021Generic · NetworkControl Module Wake-up Circuit B Performance
- U3022Generic · NetworkIgnition Input Accessory/Off
- U3023Generic · NetworkControl Module Input Power Circuit A - Ignition Input On/Start Circuit Correlation
- U3024Generic · NetworkControl Module Input Power Circuit B - Ignition Input On/Start Circuit Correlation
- U3025Generic · NetworkControl Module A Disable Circuit/Open
- U3026Generic · NetworkControl Module A Disable Circuit Low
- U3027Generic · NetworkControl Module A Disable Circuit High
- U3028Generic · NetworkControl Module A Disable Feedback Circuit
- U3029Generic · NetworkControl Module A Disable Feedback Circuit Low
- U302AGeneric · NetworkControl Module A Disable Feedback Circuit High
- U302BGeneric · NetworkIgnition Output Accessory/On/Start
- U302CGeneric · NetworkIgnition Output Off/On/Start
- U302DGeneric · NetworkIgnition Output On/Start
- U302EGeneric · NetworkIgnition Output On
- U302FGeneric · NetworkIgnition Output Accessory
- U3030Generic · NetworkIgnition Output Start
- U3031Generic · NetworkIgnition Output Off
- U3032Generic · NetworkIgnition Output Accessory/Off
- U3033Generic · NetworkControl Module Security Certificate Missing/Invalid
- U3034Generic · NetworkCommunication Authentication Key/Certificate Missing/Invalid
- U3035Generic · NetworkCommunication Authentication Signal Invalid Data
- U3036Generic · NetworkCommunication Authentication Signal Performance
- U3500Generic · NetworkControl Module Input Power A Circuit Range/Performance
- U3501Generic · NetworkControl Module Input Power A Circuit Low
- U3502Generic · NetworkControl Module Input Power A Circuit High
- U3503Generic · NetworkControl Module Input Power A Circuit Intermittent/Erratic