Airbag control unit with part number 4F0959655Q

What does the airbag control unit 4F0959655Q do?

The airbag control unit 4F0959655Q forms the evaluation unit of the restraint system (SRS) at Audi. It evaluates the crash sensors and, in an accident, decides within milliseconds which airbags and seatbelt pretensioners to trigger. After an accident it stores crash data and locks itself.

It monitors the system constantly and shows faults via the airbag warning light in the instrument cluster.

The unit is thus both evaluator and guardian.

Why does the control unit 4F0959655Q fail?

The most common cause is crash data that remains stored in the unit after an accident, even without an airbag deployment. A normal diagnostic tool cannot erase it. Alongside this are aged electronic components, cold solder joints, moisture and corrosion at plug connectors, and voltage peaks, for example from a weak battery or jump-starting.

The unit keeps this data in memory even if nothing has happened to the airbags.

The other causes creep in gradually. Over time components age, solder joints can give way, and moisture attacks the contacts.

Voltage peaks act on the electronics when the battery is weakening or when external power flows during starting.

How can you tell that the 4F0959655Q is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently if a defect is present on the 4F0959655Q. Accompanying signs can be an error message in the instrument cluster, a disturbed connection to the diagnostic tool, and a fault memory that cannot be cleared.

In an emergency this means that airbags and seatbelt pretensioners may not trigger.

So have the system checked promptly.

Which vehicles is the 4F0959655Q fitted in?

The control unit 4F0959655Q is fitted in these vehicles: Audi A6 C6 4F (2004-2008) and C6 4F Facelift (2008-2011). The part number applies to exactly this unit, not to a car as a whole.

The following vehicles are recorded for this part number:

• Audi A6 C6 4F (2004-2008)
• Audi A6 C6 4F Facelift (2008-2011)

First check the part number on the label of the removed unit against this page. This merely ensures that it is the right unit. Have the fault memory read out in advance, because only this protocol shows whether the control unit is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 4F0 910 655 D, 4F0 910 655 Q, 4F0 959 655 B, 4F0 959 655 E, 4F0 959 655 G, 4F0910655B.

How does the repair of the 4F0959655Q work?

First have the fault memory read out and enclose the log. Then disconnect the battery and afterwards remove the control unit. Finally, create a repair order online and send the unit in well packed.

Airbag24 tests the unit on the test bench. We repair defective components and delete stored crash data, then the function test follows. Then the unit goes back to you.

Processing usually takes 3–4 working days.

Our repairs come with 2 years' statutory liability for defects. The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.

How does the control unit 4F0959655Q get to Airbag24?

You send the unit as a parcel or book a UPS collection for an extra charge. For the return after repair, Airbag24 likewise uses UPS.

Put the printed repair order into the parcel, and the unit is packed shockproof.