C0020: ABS Pump Motor Control

What it means

This code identifies a fault in the ABS pump motor control function. The specific electrical or performance fault depends on the reported failure subtype and vehicle diagnostics.

How it works

The ABS pump motor moves brake fluid within the hydraulic unit so the system can build or manage pressure during ABS operation. C0020 identifies a pump-motor control fault, but the specific electrical or performance condition depends on the failure subtype reported by the vehicle.

Common causes

Most likely first.

1. Pump motor seized after long inactivity
2. Pump motor relay welded or open
3. Power supply connection corroded

Symptoms

• ABS warning light on
• ESC/stability control deactivated
• Possible reduced brake assist
• Speedometer may behave erratically

How to diagnose it

1. Read the full ABS code and failure subtype, plus freeze-frame data, because C0020 alone does not identify the exact pump-control failure.
2. Inspect the pump-motor power connections, grounds, and wiring for corrosion, looseness, or heat damage.
3. Check the pump fuse and relay, including whether the relay is open, stuck, or showing damaged contacts.
4. Verify the pump’s power supply and ground under the conditions specified by the manufacturer.
5. Use an ABS-capable scan tool and the manufacturer’s procedure to command the pump and assess its response.
6. If supply and control are correct but the motor does not run or performs poorly, evaluate the pump motor and ABS hydraulic unit.

Common fixes

• Clean and secure corroded pump-motor power or ground connections.
• Repair damaged wiring or replace a failed fuse or relay.
• Replace a seized or electrically failed ABS pump motor if confirmed by testing.
• Repair or replace the ABS hydraulic unit if the pump or its control is faulty internally.

Can I keep driving?

The vehicle may still have conventional braking, but ABS and stability control can be unavailable. Drive cautiously, leave extra stopping distance, and get the ABS fault checked promptly; avoid driving if braking feels abnormal.