U0013
Medium Speed CAN Communication Bus (-) Low
The CAN-Low signal of the medium-speed bus is shorted to ground. Comfort and body modules can no longer exchange messages and trigger several user-visible faults at once (windows, locking, lighting).
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
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
Common causes
Ordered by how often each turns out to be the cause.
- CAN-Low shorted to groundCommon
- Water ingress in door connectorPossible
- Gateway module routing CAN messages incorrectlyLess likely
Parts involved
- CAN Low Wire
- Body Control Module
U0013 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.