U3012
Control Module Improper Wake-up Performance
The control module did not wake up cleanly from sleep mode — wake event timing or sequence outside spec.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
Ordered by how often each turns out to be the cause.
- Module internal faultCommon
- Wake signal noise or glitchPossible
- Gateway module routing CAN messages incorrectlyLess likely
Parts involved
- Control Module
- Wakeup Circuit
U3012 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.