Network
generic / SAE
U0040
Communication Bus Off
A control module has counted enough transmit errors to enter the bus-off state defined by ISO 11898 and stops transmitting on the bus. Multiple modules typically lose communication and several warning lamps illuminate at once.
SystemNetwork
Typegeneric / SAE
GroupU0
Range / number– / 40
Possible causes
- CAN line shorted to supply or ground high
- Terminating resistor failed medium
- Gateway module routing CAN messages incorrectly 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: 80–1500 €
- Estimated time: 1–6 h
- Component: can bus wiring
- Component: can terminating resistor
- MIL / check engine light
- limp mode possible
Sources
References
sae:J2012
iso:11898