OBD-II code · Network
U0045 Vehicle Communication Bus B (-) shorted to Bus B (+)
The two lines of differential bus B are shorted together. 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 U0045?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyBus lines shorted together
- 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 B Wiring
Related codes
- U0036Vehicle Communication Bus A (-) shorted to Bus A (+)
- U0054Vehicle Communication Bus C (-) shorted to Bus C (+)
- U0063Vehicle Communication Bus D (-) shorted to Bus D (+)
- U009AVehicle Communication Bus H (-) shorted to Bus H (+)
- U0042Vehicle Communication Bus D (+) Open
- U0043Vehicle Communication Bus B (-) Low
- U0044Vehicle Communication Bus B (-) High
- U0046Vehicle Communication Bus C
- U0047Vehicle Communication Bus C Performance
- U0048Vehicle Communication Bus C (+) Open
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.