U009AVehicle Communication Bus H (-) Shorted to Bus H (+)
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- U009A means the two wires of Vehicle Communication Bus H touch each other, on a CAN CAN-Low against CAN-High. No manufacturer documentation of U009A is public. On a high-speed CAN this ends all traffic; onsemi's bench node could not send and drew about 47 mA against roughly 65 mA on a healthy bus. A fault-tolerant low-speed CAN can live with it: the TJA1055 from NXP initially reads the bus as constantly dominant, and only once a time-out has run does it disable its CANL driver and carry on single-wire, returning to differential operation once the wires are separated. So on some cars U009A comes with a dead network, on others only with a stored code. Separating harness sections while measuring resistance between the wires narrows down the spot.
- What you may notice
- On high-speed CAN: complete loss of Bus H functions
- Lost-communication codes for several modules
- Likely causes
- LikelyBus wires crushed together
- PossibleWet or corroded splice joining both wires
- RareInternal short in a module's transceiver
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.