Audi A4: Restraint System Pyrotechnic, Electric and Mechanical Components, Replacing After a Collision

Special tools and workshop equipment required

• Vehicle Diagnostic Tester

The airbag control module must be replaced

• If the display "Control module faulty" appears after checking the DTC memory
• After three side/ driver/ front passenger airbag or belt tensioner deployments
• If housing is damaged
• If there is deformation on the tunnel within a 200 mm (7.87 in.) radius around the control module

Always replace the following

• All deployed airbag units

Also with front passenger airbag deployment

• Instrument panel
• Deformed front passenger module supports (cannot be reformed)
• All front airbag sensors on the front end
• Remaining transverse acceleration sensors if the mounting points are deformed in the sensor area

Also with driver airbag deployment:

• Return spring with slip ring
• All front airbag sensors on the front end
• Remaining transverse acceleration sensors if the mounting points are deformed in the sensor area

Also with thorax airbag deployment

• Pressure sensors on the deployed side
• Transverse acceleration sensors on the deployed side
• Cover
• Cushion
• With a folding rear seat backrest: side cushion (if equipped)
• Remaining transverse acceleration sensors if the mounting points are deformed in the sensor area

Also

• All automatic belt retractors with deployed belt tensioners.
• All automatic belt retractors with deployed seat belt force limiters (depending on vehicle equipment)
• Seat belt latches for all automatic belt retractors with deployed seat belt tensioners with the belt on
• Seat belt height adjuster (manual and power) for all automatic belt retractors with deployed seat belt tensioners with the belt on

- Connect the Vehicle Diagnostic Tester if there is a chance the belt tensioner and/or seat belt force limiter deployed.

- In "Guided Fault Finding" under "15 - Airbag", check whether there is a crash entry in the airbag control module.

- Also check if the "Resistance too high" error is stored for the belt tensioner and/or belt force limiter. Deployed belt tensioners and/or belt force limiters must fulfill both conditions. "Requirement: the airbag control module was not replaced yet".

  Note

• The "Resistance too high" error may also be stored if there is an open circuit. Then there is normally no crash entry.
• Depending on the crash, the belt tensioner may have deployed while the belt force limiter did "NOT". In that case, follow the disposal information for pyrotechnic components. Refer to → Chapter "Airbag, Belt Tensioner and Battery Cut-Out Units, Storing, Transporting and Disposing (Pyrotechnic Components)".
• Also check the seat belts. Refer to → Chapter "Seat Belts, Checking".

- If parts of the seat belt system are removed due to an accident, replace the belt system bolts.

- If needed (visual inspection), the following must also be replaced: all faulty components.

- After replacing the airbag units or the control module, apply stickers (only tear-off strips) to the registration card and return the registration card to the appropriate distribution center or importer for registration.

Airbag Fasteners, Checking After Collision

All damaged fastening elements must always be replaced. Reshaping the components or "making them fit" is not permitted.

The following components must be checked after every airbag deployment.

With front passenger airbag deployment

• Instrument panel central tube; front passenger airbag supports and passenger airbag unit must be installed free of tension. Otherwise the central tube is to be replaced.
• Check the glove compartment for damage. Replace the glove compartment if damaged.

With driver airbag deployment

• Steering wheel: Remove the steering wheel and place it with the steering wheel rim on a flat surface. The entire steering wheel rim must rest on the surface. Otherwise the steering wheel should be replaced.
• Check steering wheel for smoke residue. If smoke residue is present, replace the steering wheel.

Collision without Airbag Deployment

• If the Airbag Indicator Lamp -K75- does not indicate a malfunction, then it is not necessary to replace the pyrotechnic components. Seat belts must be checked separately.

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