The brief
Ms Cheryl's Golf flashed an ABS error on the dashboard, so she called us for help. The ABS, the anti-lock brake system, is what keeps the wheels from locking under heavy braking so you keep control, and when it's not working you risk skidding and loss of traction in an emergency stop, so it's not one to ignore. The ABS pump is the hydraulic unit that does the work, modulating the brake pressure to each wheel, and it relies on the wheel speed sensors for its information. Often an ABS error is fixed by replacing a faulty wheel sensor. But sometimes the pump itself has failed, and then the sensor isn't the answer, the pump is. A failed ABS pump doesn't recover, so it gets replaced and coded to the car.
The diagnosis
The scan showed the ABS error went past the usual wheel sensor and pointed at the ABS pump itself, which had failed, which is why the system was down. The wheel sensors and the wiring were fine. That's an ABS pump replacement with coding to the car and the brakes bled, rather than a wheel sensor that wasn't the problem.
The work
The car was lifted, the failed ABS pump removed and a new genuine VW-spec pump fitted, every fastener and brake line torqued to the manual figures, and the pump coded and programmed to the car. The brakes were bled, the fault codes cleared, and the ABS and stability system checked. A road test confirmed the ABS working, no ABS error, the brakes firm and even, and no warning lights, all turned around within the day.
The outcome
The ABS working as it should, no ABS error on the dash, the brakes firm and even, and no warning lights, returned within a day. Ms Cheryl got the Golf back with the ABS sorted. Reading the fault properly meant we replaced the pump that had actually failed rather than throwing a wheel sensor at it, and coding it in is what brings the system back online.