What it means
The control module compares supply voltage circuits A and B for the ABS pump motor. It sets this code when their readings do not agree within the expected range.
At a glance
- Usually lights the ABS or stability-control warning light
- The engine or gearbox may go into limp mode
How it works
The ABS control module compares supply circuits A and B feeding the pump motor. This code sets when the two circuit readings disagree beyond the expected range, indicating that one supply path may have excessive resistance or an electrical fault.
Common causes
Most likely first.
- High resistance in one supply circuit
- Poor connection or damaged wiring
- Fuse or power supply fault
- Control module fault
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
How to diagnose it
- Save freeze-frame data and compare live voltage readings for pump supply circuits A and B, noting when their readings diverge.
- Inspect both supply paths, connectors, grounds, and fuses for corrosion, looseness, heat damage, or broken wiring.
- Check each circuit's voltage drop under pump load using the manufacturer's procedure to identify a high-resistance path.
- Verify fuse and power supply continuity on both A and B circuits, then check for intermittent changes while moving the harness.
- If both circuits and their connections meet specification, test the pump and control module before considering module replacement.
Common fixes
- Clean and tighten a poor connection on the supply circuit that tests out of range.
- Replace a blown fuse after finding and correcting the cause of the overcurrent.
- Repair damaged wiring or replace corroded or heat-damaged terminals in circuit A or B.
- Replace a faulty pump motor or control module only after both supply circuits pass their checks.
Can I keep driving?
ABS and stability control may be disabled, with possible reduced brake assist. Drive only as needed to reach a safe place; avoid high speeds and hard stops, and stop if braking feels abnormal.
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.