U0047Vehicle Communication Bus C Performance
- Generic OBD-II code · Network
- How the car detects it
- U0047 says that Vehicle Communication Bus C is up but its traffic is not dependable, for instance through sporadic error frames, messages arriving too late or brief dropouts. CAN controllers keep score with error counters: as onsemi explains with reference to ISO 11898-1, every failed transmission adds eight to the transmit counter, beyond about 128 the node turns error passive and past 255 it takes itself off the bus, rejoining only after 128 runs of eleven recessive bits. A performance code is typically set somewhere along that path, before or between short bus-off episodes. No manufacturer documents U0047 publicly; CARB only requires faults in digital communication to be detected and stored separately. Loose terminals, corroded connectors, interference and a node that resets now and then are the usual causes.
- What you may notice
- Functions drop out briefly and return
- Sporadic warning messages from several systems
- Likely causes
- LikelyLoose or corroded terminals on Bus C
- PossibleA module on Bus C resetting because of weak supply or ground
- RareInterference coupled into the bus wiring
- 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.