Mercedes-Benz W203 steering angle sensor and ESP light
Why is the W203 ESP light on after the battery has been disconnected?
The steering angle sensor has to be relearned. Start the car and turn the steering wheel from lock to lock a couple of times. If there is no fault, the light goes out after a few hundred metres of driving or a few starts. Otherwise the fault code is cleared with a workshop diagnostic tool.
Can a crooked steering wheel turn on the ESP light?
Yes. ESP compares the steering angle with the wheel speeds and the acceleration sensor, so a small offset in the steering wheel gives wrong information. Steering wheel straightness is checked with a diagnostic tool, not by eye. The fix is steering wheel alignment and a four-wheel alignment, and the position is adjusted with the tie rods.
What else can be behind the ESP message?
A weak battery or alternator, the brake light switch, the wheel speed sensors and the lateral acceleration sensor. The pins of the ABS pump connector can also oxidise. Brakes and ESP are important for safety, so have a workshop check the fault and the result of the repair.