U0030Vehicle Communication Bus A (+) Open
- Generic OBD-II code · Network
- How the car detects it
- U0030 stands for an open circuit in the (+) wire of Vehicle Communication Bus A. What that wire is depends on the network a maker assigns to Bus A; where it is a two-wire CAN, like the sensor/hybrid CAN Audi files under this name in its 48 V mild hybrids, the (+) line is CAN-High. A break splits the bus: nodes on opposite sides lose each other, while modules sharing an intact section may still exchange frames. NXP points out that ordinary high-speed transceivers cannot recognise an interrupted wire themselves, so the module has to deduce it from missing partners or error counters. No manufacturer documents U0030 publicly; CARB only requires missing communication from digital inputs to be detected and coded separately. Check terminals, splices and the resistance between (+) and (-).
- What you may notice
- Functions served by modules beyond the break stop working
- Lost-communication codes for some modules on Bus A
- Likely causes
- Likely(+) wire of Bus A broken in the harness
- PossibleTerminal backed out or spread in a connector
- PossibleConnector left unplugged after a repair
- 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.