C0121
Valve Relay Circuit
C0121 is an OBD-II diagnostic trouble code meaning: Valve Relay Circuit. Common causes: open or short circuit in relay wiring harness, faulty valve relay. Estimated repair cost: $56–167.
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
Error C0121 by Vehicle Brand
FAQ
What does the C0121 code mean?
C0121 is an OBD-II diagnostic trouble code that indicates: Valve Relay Circuit
What causes a C0121 error code?
The most common causes of C0121 include: Open or short circuit in relay wiring harness; Faulty valve relay; Problems with the ABS control unit; Corrosion or poor contact in connectors.
How do I fix a C0121 diagnostic trouble code?
To fix C0121: Check the wiring harness for opens and shorts. Check resistance and operation of valve relay. Inspect connectors and contacts for corrosion. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with C0121?
Limited driving only, diagnose soon
How much does it cost to fix C0121?
The estimated repair cost for C0121 is $56–167. Actual cost depends on your vehicle, location, and labor rates.
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