U0011
Medium Speed CAN Communication Bus Performance
The medium-speed CAN bus is operating but with degraded performance — frame errors or excessive error counters. Comfort and infotainment functions may operate intermittently.
- Check engine light: Not always
- 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.
- Corrosion in body harness connectorsCommon
- One module sending malformed framesPossible
- Gateway module routing CAN messages incorrectlyLess likely
Parts involved
- CAN Bus Wiring
- Body Control Module
U0011 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.