OBD-II code · Network
U0066 Vehicle Communication Bus E (+) Open
Bus E high-side line open. 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 U0066?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyWire broken
- 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
- 1–5 h
- Emissions test
- Usually unaffected
- Parts involved
- Bus E Wiring
Related codes
- U0031Vehicle Communication Bus C (+) Open
- U0039Vehicle Communication Bus B (+) Open
- U0042Vehicle Communication Bus D (+) Open
- U0048Vehicle Communication Bus C (+) Open
- U0050Vehicle Communication Bus E (+) Open
- U0057Vehicle Communication Bus D (+) Open
- U0060Vehicle Communication Bus F (+) Open
- U0078Vehicle Communication Bus B (+) Open
- U008BVehicle Communication Bus G (+) Open
- U0094Vehicle Communication Bus H (+) Open
- U0063Vehicle Communication Bus D (-) shorted to Bus D (+)
- U0064Vehicle Communication Bus E
- U0065Vehicle Communication Bus E Performance
- U0067Vehicle Communication Bus E (+) Low
- U0068Vehicle Communication Bus E (+) High
- U0069Vehicle Communication Bus E (-) Open
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.