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.
Medium severity. Can I keep driving?It depends on which control module has dropped out. If it affects the engine, brakes, or steering, do not continue your trip: call for roadside assistance.
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
Most likely causes
- Bus lines shorted together
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
What each character of U0045 means
- U: Communication network
- 0: Generic code: same on every make
- 0: Subsystem depends on the code range
- 45: Specific fault in that system
Frequently asked questions
Can I keep driving with code U0045?
It depends on which control module has dropped out. If it affects the engine, brakes, or steering, do not continue your trip: call for roadside assistance.
What causes code U0045?
The most common causes are: bus lines shorted together; gateway module routing CAN messages incorrectly; cAN terminating resistor (120 Ω) drifted out of spec.
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 (+)
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.