Check Engine Code
U0121
Lost Communication With Anti-Lock Brake System (ABS) Module
Severity: medium
DIY difficulty: 3/5
Typical cost: $80–$1500
What U0121 means
ABS module has dropped off the bus. Triggers ABS warning light and disables stability control.
Symptoms
- ABS light on
- Traction control disabled
- Speedometer issues (newer cars)
Likely causes (most common first)
- Failed ABS module
- Damaged wiring
- Power/ground issue at ABS module
- CAN bus fault
Can I keep driving?
Medium — drivable but fix soon
Typical repair cost
DIY fixes can start near $80 (parts only). Shop repairs for U0121 typically run up to $1500 depending on the underlying cause and vehicle. Start with the most common cause — Failed ABS module — before throwing parts at it.
Recommended parts & tools for U0121
Our buyer’s guides cover the tools and parts that pair with AXLY:
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