Network
generic / SAE
U0029
Vehicle Communication Bus B
Generic fault on vehicle communication bus B. Used as a catch-all for unspecified problems on a secondary CAN/comfort segment.
SystemNetwork
Typegeneric / SAE
GroupU0
Range / number– / 29
Possible causes
- Intermittent wiring fault on bus B high
- Gateway module routing CAN messages incorrectly low
- CAN terminating resistor (120 Ω) drifted out of spec low
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 80–700 €
- Estimated time: 1–5 h
- Component: can bus wiring
- Component: control module
- MIL / check engine light
Sources
References
sae:J2012
iso:11898