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A common fault found in many W203 Mercedes-Benz C-Class models is a failing combination switch. This is evident by the stalk not returning to the neutral position after selecting either a left or right run. The switch will either 1) continue in the (left/right) selected position after the steering wheel has been returned to the straight ahead position following a turn or 2) the switch will not stay in the selected position and as such needs to be held in place during indicating. Here is a short explanation of how to replace this part.

Please note that not all models are identical to the below, this job was carried out on a 2001 C220 CDI, there are numerous different part numbers and the process varies slightly also.

1. Ensure the steering wheel is set in the straight ahead position and the key is removed from the ignition. Remove the steering wheel centre airbag unit by loosening the two T30 Torx bolts mounted at either side of the wheel towards the back.

T30 Torx head

2. Once loosened this will allow the airbag unit to easily pull forward, giving access to the yellow and green airbag plugs as well as a steering wheel control plug (black). To remove the airbag plugs, simply prise the centre pins up and then prise the whole plus from the wheel unit.

Airbag connectors

3. You now have access to remove the steering wheel itself, the centre nut will need to be removed using a heavy rachet or Allen key adaptor as it requires a lot of force to remove. Ensure when the wheel is coming of to note the notches on the splines which allow you to locate the centre for refitting. Feed the airbag wires through the gap.

Remove steering wheel

4. If your steering wheel is set in the correct position, you will be able to see the below three Phillips head screws which hold the steering angle sensor in place. Remove these screws and ensure it does not spin away from its relevant position when left aside. If you can not see these screws, then the wheel is in the wrong location. If you reattach the wheel to move to the right location without firstly reattaching the airbag unit, you will enter an SRS fault in the ECU which will need to be erased using a Mercedes STAR Diagnosis machine.

Clock spring/Steering angle sensor

5. You will now see the combination switch which we are trying to reach, remove the three T25 screws visible and pull both the unit (and the cruise control unit, if fitted)out of the column. Unplug the three connections and remove from the vehicle.

T30 Torx head

6. Faulty unit

T30 Torx head

7. SRS faults, if you do not have access to a diagnostic machine to clear these faults, ensure you do not turn the key on whilst the airbag unit is disconnected.

T30 Torx head

8. Install in reverse order

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