OBD-II code · Network
U0071 Vehicle Communication Bus A (+) Bus Off
The CAN controller for bus A has shut its plus driver after exceeding the SAE J2284 / ISO 11898 transmit error threshold. The node disconnects from the bus until error counters recover.
Is it safe to drive with U0071?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyPersistent short on the CAN-H wire
- PossibleOne module driving bus permanently dominant
- Less likelyGateway module routing CAN messages incorrectly
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
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Usually unaffected
- Parts involved
- Can Transceiver, Can High Wire
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.