How much does ABS module repair cost?

ABS module repairs range from $150 for wiring or relay fixes to $800-$1,200 for a full ABS control module or hydraulic pump replacement. Remanufactured modules can reduce costs significantly.

Can a low battery cause ABS and traction control warnings?

Yes, low battery voltage is a common cause of ABS and traction control warning lights. The ABS module requires stable voltage to operate correctly. A weak battery or failing alternator should be tested first.

C0121

Power Steering Assist Motor Circuit

Severeelectrical

Overview

The C0121 code indicates that the chassis control module has detected a power steering assist motor circuit condition. This diagnostic trouble code relates to the electrical control circuits within the vehicle's chassis safety systems, including ABS, traction control, and stability control. When this code is stored, one or more chassis safety features may be disabled, which can reduce braking performance and vehicle stability under adverse driving conditions.

Symptoms

Loss of traction control function
ABS warning light illuminated on dashboard
Reduced braking performance in emergency stops
Power steering assist reduced or lost

Common Causes

Poor ground connection at the ABS module
Loose or corroded connector pins
Water intrusion into electrical connectors
Faulty ABS valve body or solenoid pack

Diagnosis Steps

1Connect an OBD-II scanner and read all stored chassis trouble codes and freeze frame data
2Inspect the ABS/ESC module connectors for corrosion, damage, or loose pins
3Check the ABS fuse and relay in the fuse box; replace if blown or faulty
4Test the ABS pump motor operation using a scan tool bi-directional command
5Measure circuit voltage and ground at the ABS module with a multimeter

Estimated Repair Cost

$150 — $1,200

Cost varies by vehicle, location, and repair shop. Includes parts and labor.

Commonly Affected Vehicles

Mercedes-Benz C-ClassChevrolet SilveradoGMC SierraHonda Accord

Related Codes

C0185 C0130 C0120

More Electrical Codes

B0001Driver Frontal Airbag Deployment Loop Circuit Open

Critical

B0002Driver Frontal Airbag Deployment Loop Circuit Short to Ground

Critical

B0003Driver Frontal Airbag Deployment Loop Circuit Short to Battery

Critical

B0004Driver Frontal Airbag Deployment Loop Resistance Too High

Critical

B0005Driver Frontal Airbag Deployment Loop Resistance Too Low

Critical

B0006Passenger Frontal Airbag Deployment Loop Circuit Open

Critical

Frequently Asked Questions

Your standard brakes will still work, but the anti-lock braking function is disabled. This means wheels can lock up during hard braking, especially on wet or icy roads. Avoid aggressive driving and have the system inspected promptly.