C0020
ABS Pump Motor Circuit
The ABS control module detects an electrical fault in the pump motor circuit. Without a working pump, the system cannot build hydraulic pressure for ABS or stability control interventions and disables those functions.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: hard
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
Ordered by how often each turns out to be the cause.
- Pump motor seized after long inactivityCommon
- Pump motor relay welded or openPossible
- Power supply connection corrodedPossible
Parts involved
- ABS Pump Motor
- ABS Control Module
- Pump Motor Relay
- Power Supply Wiring
C0020 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.