What it means
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.
At a glance
- Usually lights the ABS or stability-control warning light
How it works
The ABS control module monitors supply voltage on circuit B to the pump motor while the pump operates. This code sets when the circuit B reading varies beyond the expected range, which can point to unstable power or a high-resistance connection.
Common causes
Most likely first.
- Connector with high resistance
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
How to diagnose it
- Save the freeze-frame data and check live ABS pump supply B readings to see when the voltage becomes unstable.
- Inspect circuit B wiring and connector seals for chafing, moisture, corrosion, loose pins, or pin push-back.
- With the code active, gently move the circuit B harness while watching the scan-tool reading for a change.
- Check the circuit B fuse, connections, and voltage drop under the conditions specified by the manufacturer.
- If wiring and power supply pass, test the pump motor and ABS control module inputs using the manufacturer's procedures.
Common fixes
- Repair chafed or damaged circuit B wiring and secure it away from rubbing points.
- Clean and reseat a damp or corroded pump connector; replace damaged seals or terminals.
- Repair a loose, pushed-back, or high-resistance circuit B terminal.
- Replace a faulty pump motor or control module only after circuit tests identify it as the cause.
Can I keep driving?
ABS and stability control may be unavailable, and brake assist may be reduced. Avoid hard braking and high-speed driving; if the pedal feels unusually hard or braking is weak, stop safely and arrange recovery.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.