U0121
U0121 means "Lost Communication With ABS Control Module". Severity: 🔴 High. Avoid driving if possible — this can cause damage or be a safety risk. Get it diagnosed right away.
What the U0121 code means
| Code | U0121 |
| Definition | Lost Communication With ABS Control Module |
| System | Network / Communication |
| Type | Generic (SAE standard) |
| Subsystem | — |
| Severity | 🔴 High |
Common causes of U0121
- CAN bus wiring fault
- Failed ABS module
- Connector issue
How to fix U0121
- Inspect ABS module wiring
- Check connectors and grounds
Always confirm the diagnosis with a scan tool and live data before replacing parts.
Is it safe to drive with U0121?
Avoid driving if possible — this can cause damage or be a safety risk. Get it diagnosed right away.
U0121, answered.
What does U0121 mean?
U0121 stands for "Lost Communication With ABS Control Module". It is a generic (sae standard) OBD-II network / communication trouble code.
Is it safe to drive with a U0121 code?
Avoid driving if possible — this can cause damage or be a safety risk. Get it diagnosed right away.
What causes U0121?
Common causes include: CAN bus wiring fault; Failed ABS module; Connector issue.
How do you fix U0121?
Typical fixes: Inspect ABS module wiring; Check connectors and grounds. Always confirm the diagnosis before replacing parts.