C05A8
ABS Pump Motor Supply Voltage B Circuit Range/Performance
ABS pump motor supply B drifts or fluctuates. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
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.
- Connector with high resistanceCommon
- Sensor element aged beyond calibration windowLess likely
- Sensor mounting loose - signal dampingLess likely
Parts involved
- ABS Pump Supply B
C05A8 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.