U0081Vehicle Communication Bus F Performance
- Generic OBD-II code · Network
- How the car detects it
- U0081 marks Vehicle Communication Bus F as working but unreliable: frames arrive damaged, late or not at all from time to time, while the network as a whole stays up. No manufacturer documents U0081 publicly. Jaguar Land Rover shows how close the boundary is by recording invalid serial data on Bus F as failure type 81 of U0080 instead. Where Bus F is FlexRay, as on Audi's A6/A7 link to the transmission, each transceiver can check its own output: NXP's TJA1081B raises a bus error flag whenever the level it reads back on the BP/BM pair disagrees with the data it is sending, which happens with collisions, interference or a damaged pair. CARB asks for communication errors on digital signals to be detected, not only total loss. Intermittent contacts and moisture are the usual culprits.
- What you may notice
- Functions on Bus F drop out briefly and return
- Several modules store communication codes at the same time
- Likely causes
- LikelyLoose or corroded contact in a Bus F connector
- PossibleTwisted pair of Bus F damaged or untwisted near a repair
- RareElectrical interference from an aftermarket device
- RareModule software that handles bus timing incorrectly
- Repair
- Hard · Usually a job for a workshop.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.