OBD-II code · Network
U0012 Medium Speed CAN Communication Bus (-) Open
The CAN-Low wire on the medium-speed comfort/body bus is open. Body modules such as door modules, climate control or seat modules lose communication, but powertrain functions usually stay alive.
Is it safe to drive with U0012?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyCAN-Low wire broken in body harness
- PossibleLoose body control module connector
- Less likelyGateway module routing CAN messages incorrectly
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
- 0.8–4 h
- Emissions test
- Usually unaffected
- Parts involved
- Can Low Wire, Body Control Module
Related codes
- U0009High Speed CAN Communication Bus (-) Shorted to Bus (+)
- U0010Medium Speed CAN Communication Bus
- U0011Medium Speed CAN Communication Bus Performance
- U0013Medium Speed CAN Communication Bus (-) Low
- U0014Medium Speed CAN Communication Bus (-) High
- U0015Medium Speed CAN Communication Bus (-) Shorted to Bus (+)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.