Airbag control unit with part number 4N0959655AF

What does the airbag control unit 4N0959655AF do?

The airbag control unit 4N0959655AF controls the restraint system (SRS) of Audi as its central unit. It evaluates the crash sensors, determines within milliseconds in a crash which airbags and seatbelt pretensioners are triggered, and continuously checks the entire system.

It reports faults via the airbag warning light in the instrument cluster. After an accident, it stores crash data and locks itself.

In an emergency, the effect depends on the sensors, the control unit and the triggering working together smoothly. The control unit coordinates this interplay.

Why does the control unit 4N0959655AF fail?

The most common cause on the 4N0959655AF is stored crash data after an accident, even if no airbag has triggered. Other causes include aged components, solder joints, plug connections and voltage spikes.

A standard diagnostic tool cannot erase crash data. Airbag24 erases it during the repair.

Other causes at a glance:

• aged electronic components
• cold solder joints
• moisture and corrosion at plug connections
• voltage spikes, for example from a weak battery or jump-starting

How can you tell that the 4N0959655AF is defective?

A defect in the 4N0959655AF shows up in several signs in the vehicle and on the diagnostic tool. In an emergency, airbags and seatbelt pretensioners may possibly fail to deploy.

These signs indicate a defect:

• The airbag warning light is on permanently or intermittently.
• An error message appears in the instrument cluster.
• The diagnostic tool cannot establish a connection with the control unit.
• The fault memory cannot be cleared.

Have such signs checked promptly.

Which vehicles is the 4N0959655AF fitted in?

The control unit 4N0959655AF is fitted in these vehicles: Audi RS6 C8 (2019-2025); Audi RSQ8 4M (2019-2022) and 4M Facelift (from 2024); Audi RS7 C8 4K Facelift (2023-2025) and C8 4K (2019-2023); Audi SQ8 4M (2019-2023) and 4M Facelift (from 2023); Audi Q8 4M Facelift (from 2023) and 4M (2018-2023).

Below you will see the vehicles, each on its own line:

• Audi RS6 C8 (2019-2025)
• Audi RSQ8 4M (2019-2022)
• Audi RSQ8 4M Facelift (from 2024)
• Audi RS7 C8 4K Facelift (2023-2025)
• Audi RS7 C8 4K (2019-2023)
• Audi SQ8 4M (2019-2023)
• Audi SQ8 4M Facelift (from 2023)
• Audi Q8 4M Facelift (from 2023)
• Audi Q8 4M (2018-2023)

Comparing the part number on the label of the removed unit with this page confirms that you have the right unit. However, only the read-out fault memory is meaningful for the cause: it shows whether the control unit is defective or whether a plug or cable is behind the fault.

For the same vehicles, we also repair control units with the part numbers 4M0959655, 4M0959655AL, 4M0959655E, 4N0 959 655AE, 4N0959655A, 4N0959655AC.

How does the repair of the 4N0959655AF work?

First have the fault memory read out and attach the log, then disconnect the battery. Only then remove the control unit 4N0959655AF and create a repair order online. At Airbag24, processing usually takes 3–4 working days.

Airbag24 checks the control unit, replaces defective components, erases the crash data and carries out a function test. Your own unit is then returned to you.

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 4N0959655AF get to Airbag24?

Either you send the control unit 4N0959655AF as a parcel, or you book a UPS collection for an extra charge. Airbag24 returns it to you after the repair via UPS.

Put the printed repair order into the parcel and pack the unit so that it is shock-proof.