C0121

Valve Relay Circuit

Severity

🔴 High

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$56–167 (est.)

Symptoms

The ABS/ESP indicator on the dashboard is on
Disabling the ABS or ESP system
Unstable operation of the brake system

Causes

Open or short circuit in relay wiring harness
Faulty valve relay
Problems with the ABS control unit
Corrosion or poor contact in connectors

How to Fix

Check the wiring harness for opens and shorts
Check resistance and operation of valve relay
Inspect connectors and contacts for corrosion
Scan the ABS control unit for additional errors
Replace relay or wiring harness if necessary

Related codes

C0110 C0122 C0123