U0087Vehicle Communication Bus F (-) High
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- U0087 stands for a (-) wire on Vehicle Communication Bus F pulled too high, most often through contact with battery voltage. If Bus F is the FlexRay of an Audi A6/A7, the wire is bus minus (BM); held above BP, it creates a constant negative difference that receivers treat as DATA_0, so the channel looks permanently busy and no node can place a frame. NXP's TJA1081B tolerates such a short on its bus pins without damage. On a CAN, CAN-Low at supply voltage cannot be pulled down for a dominant bit; onsemi and NXP both describe the bus as blocked. Volvo includes a short of CAN-Low to power among the causes of its truck code U008088. No manufacturer documents U0087 itself. With ignition on, a (-) wire near battery voltage confirms the fault.
- What you may notice
- All functions on Bus F fail together
- Warning lamps and messages from several systems
- Likely causes
- Likely(-) wire of Bus F shorted to a battery or ignition feed
- PossibleMoisture in a connector linking the (-) pin to a supply
- RareInternally shorted transceiver in one module
- Repair
- Hard · Usually a job for a workshop.Typical cost: €60 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.