Necessary preliminary tasks

WARNING: This page is about a different car, the 2011 BMW 328xi, 2010 BMW 335xi, 2010 BMW 328xi, 2009 BMW 335xi, and 2009 BMW 328xi. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect BATTERY NEGATIVE LEAD. See 6120900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD (E90) or 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD (E92) .
Remove shift paddles for automatic transmission

Insert Torx screwdriver (T25) at an angle into concealed opening on reverse side of steering wheel until a spring resistance is felt (approx. 1.5 cm).

Increase pressure on spring leg (concealed) using Torx screwdriver (T25) until airbag unit is unlocked.

Repeat procedure on other side.

Installation:

Make sure electrical leads are correctly positioned.

Fig 1: Inserting Torx Screwdriver (T25) At An Angle Into Opening

Courtesy of BMW OF NORTH AMERICA, INC.

Snap airbag unit with uniform pressing force plane-parallel in direction of steering column shaft into steering wheel.

WARNING: Risk of injury!
Airbag unit may only be set down with the airbag itself facing upwards.

Tilt airbag unit forwards.

Disconnect plug connections and remove airbag unit.

Installation:

Connect plugs to connections of same color on airbag unit.

Fig 2: Locating Plug Connections And Airbag Unit

Courtesy of BMW OF NORTH AMERICA, INC.