Severity: Moderate
Drivable, but it can cause more damage or poor economy. Get it checked within days.
What U0121 means
Lost communication with the ABS module. ABS and stability control are usually disabled.
Symptoms
- ABS and traction lights on
- Speedometer issues on some models
Common causes
Most likely first
- 1ABS module power or ground
- 2Network wiring
- 3Failed module
How we diagnose it
- Check ABS fuses and grounds
- Network test
Every vehicle sets codes under its own conditions. We check the factory diagnostic steps and service bulletins for your VIN, so the repair targets the actual cause.