Audi TT RS FV airbag control unit repair

What is an Audi TT RS FV airbag control unit?

In the Audi TT RS FV, the airbag control unit acts as the higher-level control unit of the restraint system (SRS). It evaluates the signals from the crash sensors and, in an accident, triggers exactly the airbags and seatbelt pretensioners that are needed within milliseconds. At the same time it monitors the system continuously and makes faults visible via the airbag warning light.

The unit is fitted in the Audi TT RS FV (2016 to 2023). When the ignition is switched on, it checks whether sensors, igniters and other components of the system respond, and stores every anomaly in the fault memory, which a workshop can later read out with a diagnostic tool.

If an accident occurs, the control unit stores crash data and locks itself. Failures are also possible without an accident, namely when the electronics in the unit itself report a fault or stop responding altogether.

Why is the Audi TT RS FV airbag control unit defective?

Most often the cause is crash data that remains in the unit after an accident, even if no airbag has deployed. Ageing electronic components, cold solder joints, moisture and corrosion at the connectors, as well as voltage spikes, are also possible triggers.

A standard diagnostic tool cannot delete this stored crash data, even if no airbag has deployed. Voltage spikes occur, for example, when the battery is weak or when the car is jump-started, and over a longer period ageing and moisture also affect the circuit board.

A defect is indicated when the airbag warning light stays on permanently, the fault memory cannot be reset, or the diagnostic tool cannot establish contact with the control unit. With any of these signs it makes sense to have the unit checked.

Common error codes for Audi TT RS FV airbag control unit repair

The codes known for the Audi TT RS FV relate to the supply voltage, an internal defect of the control unit and the firing circuits of the front and side airbags. Which of them is stored in your case depends on the equipment and the type of damage.

The list below is a guide to codes that can occur on this vehicle. Your diagnostic tool may display them in a different notation.

• 65535 → Control unit reports internal defect
• 00532 → Supply voltage too low, sporadic
• 00588 → Driver airbag firing circuit, resistance fault
• 00590 → Passenger airbag igniter faulty
• 01217 → Front side airbag firing circuit, driver side, resistance fault
• 01218 → Front side airbag firing circuit, passenger side, resistance fault

The codes are read out with a diagnostic tool. A single entry does not yet prove that the control unit itself is defective, as connectors, wiring or an airbag module may equally be behind it. Where the cause lies only becomes clear during the inspection.

What part numbers are available for the Audi TT RS FV airbag control unit repair?

On the label on the unit you will find the part number, which defines the exact version of the airbag control unit in the Audi TT RS FV. Depending on equipment and year of manufacture, different numbers occur within one model series.

Known numbers for this vehicle are listed below, although the list need not be complete.

• 5Q0959655R

Compare the number on your own unit with this list. This only ensures that you have the right unit in front of you. Whether it is actually defective only becomes apparent when the fault memory is read out or during the inspection.

The route to repair looks like this: have the fault memory read out, disconnect the battery and remove the control unit. Then create a repair order online and send the unit to Airbag24. Inspecting, repairing and testing usually take 3–4 working days at Airbag24.

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.