C0121Medium urgency

Valve Solenoid Circuit Malfunction

Chassis · ABS System

⚠️ Fix soon — ABS may not function in emergency braking.

What this means

A solenoid valve in the ABS hydraulic control unit has a circuit fault. ABS solenoids rapidly modulate brake pressure during an ABS event.

Likely causes

Estimated repair cost

ABS solenoid replacement$100 – $400

ABS HCU replacement$400 – $1,200

ABS module replacement$300 – $900

Frequently asked questions

A solenoid valve in the ABS hydraulic control unit has a circuit fault. ABS solenoids rapidly modulate brake pressure during an ABS event.

Fix soon — ABS may not function in emergency braking.

Repair costs for C0121 range from $100 – $400 depending on the root cause and your vehicle.

You can drive short distances but should have it repaired within 1-2 weeks to prevent further damage.