Block of codes
U30xx codes: control module power, ignition and wake-up
This block brings together the codes from U3000 to U302F in the glossary. Open yours to see what it means, its causes and whether you can keep driving.
Reviewed by Daniel Morales, founder of Reprorace SL, on
What this block covers
Communication network
Control units talk to each other over buses such as CAN. A U code means one control unit has stopped hearing another: the cause may be that other unit, the wiring or the power supply, often a low battery.
The 48 codes of the block
- U3000Control module: malfunction
- U3001Control module: incorrect shutdown
- U3002Vehicle identification number: malfunction
- U3003Battery voltage: malfunction
- U3004Accessory power relay: malfunction
- U3005Retained accessory power: malfunction
- U3006Control module input power A, circuit open
- U3007Control module input power B, circuit open
- U3008Control module ground A: malfunction
- U3009Control module ground B: malfunction
- U300AIgnition switch: malfunction
- U300BIgnition input accessory/on/start: malfunction
- U300CIgnition input off/on/start: malfunction
- U300DIgnition input on/start: malfunction
- U300EIgnition input "on": malfunction
- U300FIgnition input accessory: malfunction
- U3010Ignition input start: malfunction
- U3011Ignition input: bus off
- U3012Control module: incorrect wake-up
- U3013Control module input power C, circuit open
- U3014Control module input power D, circuit open
- U3015Control module ground C: malfunction
- U3016Control module ground D: malfunction
- U3017Control module timer/clock: performance
- U3018Control module input power circuit A/B: correlation fault
- U3019Control module input power circuit B/C: correlation fault
- U301AControl module, wake-up circuit: open circuit
- U301BControl module, wake-up circuit A: signal low
- U301CControl module, wake-up circuit A: signal high
- U301DControl module, wake-up circuit A: performance
- U301EControl module, wake-up circuit B open
- U301FControl module, wake-up circuit B: signal low
- U3020Control module, wake-up circuit B: signal high
- U3021Control module, wake-up circuit B: performance
- U3022Ignition input accessory/off: malfunction
- U3023Correlation fault between control module input power circuit A and ignition input on/start circuit
- U3024Correlation fault between control module input power circuit B and ignition input on/start circuit
- U3025Control module A disable, circuit open
- U3026Control module A disable, circuit: signal low
- U3027Control module A disable, circuit: signal high
- U3028Control module A disable, feedback circuit: malfunction
- U3029Control module A disable, feedback circuit: signal low
- U302AControl module A disable, feedback circuit: signal high
- U302BIgnition output accessory/on/start: malfunction
- U302CIgnition output off/on/start: malfunction
- U302DIgnition output on/start: malfunction
- U302EIgnition output "on": malfunction
- U302FIgnition output accessory: malfunction
Other blocks
Read your car's fault codes on your phone
With an ECO-LITE in the OBD socket you see the codes in your account, with the data captured when the fault happened, and your workshop can check them remotely, always with your permission.
Keep reading
- OBD fault codes: what each one means
- Check engine light on: what to do
- How to read and clear your car's fault codes
- Will your car pass its MOT or inspection with the engine light on?
- Wi-Fi OBD2 reader: which one to choose
- Reading fault codes by car make
- Remote OBD diagnostics: what it is, how it works and what it can't do
- Vehicle diagnostics glossary