U0041Vehicle Communication Bus B (+) High
- Generic OBD-II code · Network
- How the car detects it
- U0041 means the (+) wire of Vehicle Communication Bus B sits at too high a voltage, typically because it touches a battery or 5 V supply. For a high-speed-type CAN this is CAN-High, and NXP classes a short of CAN-High to battery or to VCC as a hidden failure: frames keep flowing, so only a transceiver with bus diagnosis, such as the TJA1043, reports it. On a fault-tolerant low-speed CAN NXP's TJA1055 reacts in two steps after time-outs and finally switches off its CANH driver, running on CAN-Low alone. Either way the vehicle often behaves normally, and the code may sit in memory long before anything fails. No manufacturer documents U0041 publicly. A reading near supply voltage on CAN-High against ground confirms it; check for chafing against feed wires and moisture in connectors.
- What you may notice
- Often no noticeable symptom, code found during a scan
- Sporadic warnings from one module
- Likely causes
- Likely(+) wire chafed against a battery or 5 V feed
- PossibleMoisture in a connector bridging the (+) wire to a supply pin
- RareFaulty transceiver driving the (+) line high
- 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.