U0051Vehicle Communication Bus C (-) Open
- Generic OBD-II code · Network
- How the car detects it
- U0051 stands for a severed (-) conductor on Vehicle Communication Bus C, CAN-Low where Bus C is a CAN. Deutz, which places Bus C on the fourth CAN channel of the EMR L1 engine control unit, does not use this code and books CAN 4 faults only as open circuit (U0048) or short circuit (U0054). A high-speed transceiver cannot see the interruption itself, as NXP points out, so the module only notices that partners on the far side stop acknowledging or sending. NXP's fault-tolerant low-speed TJA1055 instead compares the edge counts on both wires and flags a difference of four pulses; since that works only when the break lies between sender and receiver, its error output tends to toggle. No car maker documents U0051 publicly. Check CAN-Low continuity connector by connector.
- What you may notice
- Modules beyond the break no longer respond
- Code comes and goes while other modules keep working
- Likely causes
- Likely(-) wire of Bus C broken at a flex point or splice
- PossibleTerminal pushed back or spread in a Bus C connector
- RareCorroded splice interrupting the (-) line
- Repair
- Hard · Usually a job for a workshop.Typical cost: €60 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.