Before working on the airbag, you need to remove the red plug connector (1 and 2) from the bracket (3) on the right side of the dashboard and disconnect it.
The airbag module in the steering wheel is removed after loosening both screw connections (number "1" indicates the left one) on the back of the steering wheel.
The Audi A4 is equipped with standard airbags on the driver's side and the passenger's side next to the driver. There is one airbag under the large impact plate in the middle of the steering wheel or under the contour of the instrument panel on the right. Ignition occurs in the event of a collision with a hard obstacle at a speed of at least 18 km/h or at higher speeds in a collision between two vehicles. The force of the impact is determined by the trigger, which is located at the front under the center console. It also activates the "ignition cartridge" in the steering wheel or in the instrument panel. The airbag only provides protection in combination with the seat belts.