Summary
C0110 means the ABS/Electronic Brake Control Module (EBCM) has detected a malfunction in the ABS hydraulic pump motor circuit. The pump motor is responsible for pressurizing brake fluid during ABS, traction control, and stability control events. Without a functioning pump, these systems cannot modulate brake pressure. The most common cause is a failed pump motor (40%), followed by the pump motor relay (25%) and wiring or connector issues (15%). This is a serious fault — the pump is essential for power-assisted emergency braking functions.
Severity: High — power braking assist may be compromised
Safe to drive: No — power braking assist may be compromised, increasing stopping distances
Repair cost: $200–$1,500 depending on cause
DIY difficulty: Moderate to Hard
What does C0110 mean?
The ABS hydraulic pump motor is an electric motor inside the ABS modulator assembly (also called the hydraulic control unit or HCU). When the ABS module detects wheel lockup during braking, it commands solenoid valves to release pressure from the locking wheel. The released fluid goes into an accumulator chamber, and the pump motor pushes that fluid back into the master cylinder circuit so brake pressure can be re-applied. This cycle repeats many times per second — the pulsation you feel in the brake pedal during an ABS event.
C0110 is set when the ABS module commands the pump motor to run but does not detect motor operation, or when the motor draws excessive current, runs continuously when it should not, or fails to reach the expected speed. Some systems also set this code when the pump motor relay does not respond to commands.
This code is more serious than a wheel speed sensor fault. While sensor codes disable ABS but leave conventional brakes fully functional, a pump motor fault can affect the system's ability to manage brake pressure during emergency stops. On some vehicles with active brake boost (such as those with electro-hydraulic boost rather than a traditional vacuum booster), loss of the pump can directly reduce braking assist.