OBD-II code · Network
U0051 Vehicle Communication Bus C (-) Open
Bus C low-side line open. 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 U0051?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyWire 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
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–5 h
- Emissions test
- Usually unaffected
- Parts involved
- Bus C Wiring
Related codes
- U0033Vehicle Communication Bus A (-) Open
- U0069Vehicle Communication Bus E (-) Open
- U008EVehicle Communication Bus G (-) Open
- U0097Vehicle Communication Bus H (-) Open
- U0048Vehicle Communication Bus C (+) Open
- U0049Vehicle Communication Bus C (+) Low
- U0050Vehicle Communication Bus E (+) Open
- U0052Vehicle Communication Bus C (-) Low
- U0053Vehicle Communication Bus C (-) High
- U0054Vehicle Communication Bus C (-) shorted to Bus C (+)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.