U0033Vehicle Communication Bus A (-) Open
- Generic OBD-II code · Network
- How the car detects it
- U0033 reports an interruption of the (-) wire of Vehicle Communication Bus A; on a dual-line CAN like the sensor/hybrid CAN Audi lists as Bus A, that is CAN-Low. As with U0030, the network falls apart into pieces that can no longer hear each other, and NXP stresses that a standard high-speed transceiver has no means of detecting an open wire on its own. The control module infers the fault indirectly, for example from expected messages that stop arriving or from rising error counters, so the code often appears next to lost-communication entries for modules beyond the break. No manufacturer documents U0033 publicly. With the battery disconnected, a resistance between (+) and (-) that differs from the normal termination value hints at the break; check recently separated connectors first.
- What you may notice
- Modules beyond the break stop responding
- Lost-communication codes stored alongside
- Likely causes
- Likely(-) wire of Bus A broken in the harness
- PossiblePushed-back or corroded terminal in a connector
- PossibleConnector not reconnected 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.