U0121
Fix soonBrakes & stabilityLost communication with ABS module
The ABS module isn't responding on the bus.
Common causes
- Failed ABS module
- Wiring
- Module power issue
Can I keep driving?
Short trips only. Book a diagnosis soon — driving on this fault can damage other parts.
Who fixes U0121
This one falls under ABS / ESP calibration. Verified specialists can read it live over a remote session, usually in a few minutes — you only pay if it works.
Full guide
U0121 meaning: Lost Communication With ABS Module ExplainedLearn what U0121 means, common causes, live scan data, DIY checks, and when to consult a specialist.Related codes
These explanations are from a curated DTC knowledge base. Manufacturer-specific codes may need a specialist's hands-on read.