Removing and installing the airbag unit on the Mercedes-Benz W203 steering wheel

Airbags 
 

1 - Driver airbag  2 - Front passenger airbag  3 - Head airbag	4 - Side airbag rear  5 - Side airbag front

Withdrawal

PROCEDURE 

Familiarize yourself with the safety precautions for handling the airbag.

1. Disconnect the negative (-) battery cable with the ignition off. The cabin air filter box must first be removed.

2. Isolate both poles of the battery to prevent accidental contact. 
3. Fully pull out the steering wheel by releasing the lock lever.

4. Turn out from within through apertures on a steering wheel (1) two screws with internal hexagon on 30 mm, thus holding the block of an airbag.   In the illustration, the airbag unit has already been removed. (2) - turn indicator switch.

5. Remove the block of an airbag (3) from a steering wheel and disunite a socket (4) a fuse.

6. Lay the airbag unit so that the steering wheel cushion is facing up.

Installation 

PROCEDURE

1. Place the airbag unit on the steering wheel and fix the connector until you hear a distinct click. 
2. Lubricate the mounting bolts with thread locking compound and tighten to 6Nm. 
3. Attach a cable of weight (-) of the storage battery at the switched off ignition. Install the cabin air filter box. If necessary, enter the radio code and set the time on the clock.

Sources: http://www.auto-knigi.com/model/mb_c/12_5_3/