Mercedes-Benz W203 ABS, ESP and BAS lights on
Why are the W203 ABS, ESP and BAS lights on at the same time?
The lights usually come on when a sensor or the pump in the system reports an error. Common causes are worn brushes in the ABS/ESP pump motor, poor contact in the pump's cable connector, a wheel speed sensor, the brake light switch and the steering angle sensor. The cause is located by reading the fault codes with a diagnostic tool.
Can worn ABS/ESP pump brushes turn the lights on?
Yes, it is one of the most common causes. The brushes of the pump's electric motor wear out, and the lights come on or flash. The brushes can be renewed without replacing the whole unit, but the lights may return, so a used pump can also be an option. Have a workshop do the work.
What else can cause an ESP warning on a W203?
A crooked steering wheel can turn on the ESP warning, for example when wheel angles have changed after work on brake or steering parts. Other causes are an offset in the steering angle sensor's zero point and the lateral acceleration sensor. Brakes are safety-critical, so have a workshop check the result of the work.