U0066Vehicle Communication Bus E (+) Open
- Generic OBD-II code · Network
- How the car detects it
- U0066 indicates a break in the (+) wire of Vehicle Communication Bus E. Where Bus E is a two-wire CAN, like the infotainment CAN Audi and Volkswagen monitor under that slot, the (+) wire is CAN-High. The physical layer decides how visible the fault is. With fault-tolerant low-speed hardware, NXP's TJA1055 rides through a CAN-High interruption with drivers, termination and differential receiver left as they were, and only counts edges: once CAN-High and CAN-Low differ by four pulses, its error output goes low. A high-speed transceiver offers no such check, so modules notice only that partners beyond the break fall silent. No manufacturer documents U0066 publicly; Audi's A3 case of a badly seated contact carrier in a multi-pin connector shows how such interruptions arise.
- What you may notice
- Modules beyond the break, often infotainment units, unreachable
- Lost-communication codes for individual modules
- Likely causes
- Likely(+) wire of Bus E broken in the harness
- PossibleContact carrier or terminal not seated in a multi-pin connector
- RareConnector 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.