OBD-II code · Network
U0046 Vehicle Communication Bus C
Generic fault on bus C (third bus, often chassis CAN or diagnostic CAN). A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
Is it safe to drive with U0046?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyWiring or node fault on bus C
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
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
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Usually unaffected
- Parts involved
- Bus C Wiring, Bus C Nodes
Related codes
- U0028Vehicle Communication Bus A
- U0029Vehicle Communication Bus B
- U0037Vehicle Communication Bus B
- U0055Vehicle Communication Bus D
- U0064Vehicle Communication Bus E
- U0089Vehicle Communication Bus G
- U009BVehicle Communication Bus I
- U009DVehicle Communication Bus J
- U0043Vehicle Communication Bus B (-) Low
- U0044Vehicle Communication Bus B (-) High
- U0045Vehicle Communication Bus B (-) shorted to Bus B (+)
- U0047Vehicle Communication Bus C Performance
- U0048Vehicle Communication Bus C (+) Open
- U0049Vehicle Communication Bus C (+) Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.