Airbag control unit with part number 8W7 959 655

What does the airbag control unit 8W7 959 655 do?

The airbag control unit 8W7 959 655 is the central control unit of the restraint system (SRS) for Audi. It evaluates the crash sensors, decides in an accident whether the airbags and seatbelt pretensioners fire, and monitors the system continuously. After an accident, it stores crash data and locks itself.

In operation the unit works unobtrusively in the background. It checks the power supply, the connections and the firing circuits.

As soon as it detects a fault, it creates an entry in the fault memory and shows the fault via the airbag warning light in the instrument cluster.

Why does the control unit 8W7 959 655 fail?

Stored crash data after an accident is the most common cause, even if no airbag has deployed. Ageing electronics, cold solder joints, moisture and corrosion at plug connections, and voltage spikes are also among the possible reasons.

A normal diagnostic tool cannot erase crash data. This makes troubleshooting noticeably harder.

The other reasons develop gradually. Electronic components age, solder joints can loosen, and moisture attacks contacts. A weak battery or a jump start can produce voltage spikes that stress the control unit.

How can you tell that the 8W7 959 655 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently, a fault message appears in the instrument cluster, the diagnostic tool finds no connection to the control unit, and the fault memory cannot be cleared.

As long as such a fault exists, airbags and seatbelt pretensioners may not deploy in an emergency. The warning light makes the defect visible and is a clear warning sign.

If the light comes on, have the system checked promptly to narrow down the cause.

Which vehicles is the 8W7 959 655 fitted in?

The airbag control unit 8W7 959 655 is fitted in these vehicles: Audi S5 F57 Convertible (2017-2019) and F57 Convertible Facelift (2019-2024).

The list of vehicles with this control unit:

• Audi S5 F57 Convertible (2017-2019)
• Audi S5 F57 Convertible Facelift (2019-2024)

Compare the part number on the label of the removed unit with this page. This only confirms that it is the correct unit. Have the fault memory read out beforehand. Only this result 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 8W0 959 655 M, 8W0 959 655 P.

How does the repair of the 8W7 959 655 work?

First have the fault memory read out and enclose the log, then disconnect the battery and remove the control unit. Create a repair order online and send the unit in well packed. Processing at Airbag24 usually takes 3–4 working days.

At Airbag24 the unit is checked on the test bench, defective components are replaced, the crash data is erased and a function test is carried out.

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 8W7 959 655 get to Airbag24?

You send the unit as a parcel or, for a UPS collection for an extra charge, book one. After the repair, Airbag24 returns it to you by UPS.

Print out the repair order and put it in the parcel. Pack the control unit shockproof.