OBD-II code · Network (extended)
U301A Control Module Wake-up Circuit A/Open
Open circuit on the wake-up signal line A — module cannot be woken from sleep via this path. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
Is it safe to drive with U301A?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyWake-up wire broken
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
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
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Wakeup Circuit A, Wakeup Wiring
Related codes
- U301EControl Module Wake-up Circuit B/Open
- U3017Control Module Timer/Clock Performance
- U3018Control Module Input Power Circuit A/B Correlation
- U3019Control Module Input Power Circuit B/C Correlation
- U301BControl Module Wake-up Circuit A Low
- U301CControl Module Wake-up Circuit A High
- U301DControl Module Wake-up Circuit A Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.