Airbag units after an accident, replacing: Notes

WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 2009 Audi S4, 2009 Audi A4, 2008 Audi S4, 2008 Audi RS 4, and 2008 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

The control unit for the airbag can be used for up to three side/head airbag and/or belt tensioner deployments.
The malfunction display "Control module defective" will appear after third deployment.

Airbag control module must be replaced:

If driver/passenger airbag is deployed.
After three side and/or head airbag deployments
If housing is damaged
In the event of tunnel deformation within 200 mm radius of control unit

Always replace the following:

All triggered airbag units

Additionally, if front passengers airbag has been triggered:

Instrument panel
Supports for passengers airbag module which have been bent out of shape (must not be bent back into shape).
Both front airbag sensors on front end
Lateral acceleration sensor if floor pan around sensor has been deformed

Additionally, if drivers airbag has been triggered:

Self-cancelling ring with slip ring.
Both front airbag sensors on front end
Lateral acceleration sensor if floor pan around sensor has been deformed

Additionally, if side airbag has been triggered:

Lateral acceleration sensor on side where airbag has been triggered.
With folding backrests: Side padding.
Non-triggered lateral acceleration sensor if floor pan around sensor has been deformed.

Additionally, if head airbag has been triggered:

Lateral acceleration sensor on side where airbag has been triggered.
A, B, C and D-pillar trim
Non-triggered lateral acceleration sensor if floor pan around sensor has been deformed

Additionally:

All seat belts with triggered belt tensioners

A - Airbag control module triggered:

Connect vehicle diagnostic, testing and information system VAS 5051 A and select vehicle system "15 - Airbag". For this purpose, the ignition must be switched on.

Front belt tensioner:

Read measured value block, display group 001.

Fig 1: Diagnostic System VAS 5051: Display - Display Fields

Courtesy of VOLKSWAGEN UNITED STATES, INC.

A triggered belt tensioner is indicated by the display "too great".

Rear belt tensioner (USA):

Read measured value block, display group 002.

A triggered belt tensioner is indicated by the display "too great".

B - Airbag control module replaced:

Connect vehicle diagnostic, testing and information system VAS 5051 A and select vehicle system "15 - Airbag". For this purpose, the ignition must be switched on.
Interrogate DTC memory.

Fig 2: Identifying Content Of DTC Memory & Identification Of Fault On Diagnostic System VAS 5051 Display

Courtesy of VOLKSWAGEN UNITED STATES, INC.

A triggered belt tensioner is identified by the fault message "Belt tensioner igniter - Resistance value too great".

In addition, the following must also be replaced, if necessary (visual check): all faulty components