Airbag control unit with part number 80A 959 655 Q

What is the function of the Airbag Control Unit 80A 959 655 Q?

The Airbag Control Unit 80A 959 655 Q is the central control unit for the occupant protection system in the Audi Q5 (FY/FYB). It receives data from acceleration and crash sensors, processes this information in real time, and precisely deploys the necessary airbags and seatbelt pretensioners in the event of a collision to provide optimal protection for vehicle occupants.

As the “brain” of the safety system, this component is responsible for processing signals from the crash sensors distributed throughout the vehicle. Within milliseconds, the electronics determine which restraint systems need to be activated. The control unit selectively manages the individual ignition circuits for the driver’s airbag, passenger’s airbag, side airbags, head airbags, and pyrotechnic seatbelt pretensioners.

This part number is also listed as 80A959655Q and was specifically developed for the second generation of the Audi Q5.

Why does the 80A 959 655 Q control unit fail?

The most common cause of failure for the 80A 959 655 Q control unit is internally stored, non-erasable crash data following an accident. Additional defects arise from age-related failures of electronic components such as memory chips or voltage regulators, micro-cracks at solder joints (especially on BGA chips), and corrosion caused by moisture ingress.

After one or more airbags have been deployed, irreversible crash data is recorded in the control unit’s internal memory—either EEPROM or Flash. This lock cannot be removed using conventional workshop diagnostic tools, rendering the unit effectively unusable.

Furthermore, purely electronic causes can lead to failure. These include age-related degradation of semiconductor components like voltage regulators, driver ICs, or memory modules. Thermal stress and vibrations may also result in micro-cracks at solder connections, particularly in complex BGA chips mounted on the circuit board.

External factors such as moisture entering the vehicle interior can likewise cause corrosion on the housing, connectors, or directly on the circuit board, impairing functionality. Improper repair attempts or incorrect flashing procedures can also lead to unusual malfunctions.

How do you recognize a fault with the 80A 959 655 Q?

A defective 80A 959 655 Q primarily manifests as a continuously illuminated airbag warning light on the instrument cluster. Often, communication with the control unit via a diagnostic tool becomes impossible. The fault memory frequently contains entries such as “control unit defective,” “internal memory error,” or “crash data stored.”

The clearest indication is the permanently lit airbag warning light. In some cases, it does not illuminate immediately upon starting the engine but only after a few seconds of driving, suggesting an internal self-test error.

During diagnostics at the workshop, it often becomes apparent that the control unit is no longer reachable. Diagnostic tools like VCDS or ODIS report “control unit not responding.” If communication remains possible, typical error codes appear, pointing directly to an internal hardware defect.

Another symptom is error codes related to specific ignition circuits (e.g., driver’s airbag, knee airbag) that persist even after replacing peripheral components such as airbags or coil springs. This indicates that the root cause lies within the control unit itself.

In which models is the 80A 959 655 Q installed?

The Airbag Control Unit with part number 80A 959 655 Q is specifically designed for the second generation of the Audi Q5. At Airbag24, we repair this component for the Audi Q5 FY model series (pre-facelift and facelift) as well as for the Audi Q5 FYB Sportback, depending on the vehicle’s equipment configuration.

Repair services for this control unit are available at Airbag24 for the following vehicles and model lines:

Audi: Q5 FY (2017–2020), Q5 FY Facelift (2020–2024), Q5 FYB Sportback (2020–2024), including SQ5 variants.

How does repair work at Airbag24?

Professional repair at Airbag24 includes a detailed incoming inspection on the test bench, targeted erasure of crash data from memory (EEPROM/Flash), and replacement of defective electronic components on the circuit board. Finally, a comprehensive functional and safety check is performed to ensure full operability.

Once submitted to Airbag24, repairs follow a standardized process. First comes an initial inspection, during which the device is read out if possible. Next, the memory contents are extracted to systematically remove crash data and restore the control unit to a state free of crash records.

Simultaneously, component-level repairs take place. Defective semiconductors such as driver ICs, voltage regulators, or memory chips are identified and replaced. If contact issues are suspected, critical solder joints—especially on BGA components—are professionally reworked. Any existing corrosion damage is carefully removed.

Before being returned, each repaired control unit undergoes rigorous functional and safety testing on a specialized test bench. Here, crash signals and deployment circuits are simulated to ensure that all ignition circuits operate within specifications and no internal faults remain. We provide 2 years' statutory liability for defects on all repairs.

Is repairing the 80A 959 655 Q worthwhile?

Repairing the 80A 959 655 Q is a cost-effective and sustainable alternative to an expensive new part. Since the original control unit remains in the vehicle, critical data such as the VIN and coding are preserved, avoiding time-consuming adjustments and restoring full system functionality.

The key advantage lies in the substantial cost savings compared to purchasing a new OEM part. Additionally, the original control unit is retained, meaning vehicle-specific codings and the VIN remain unchanged—preventing compatibility issues and lengthy reprogramming after installation.

From an environmental perspective, repair is the more resource-efficient choice, as it avoids the production of a new, complex electronic module. Especially when stored crash data can no longer be erased via OBD, chip-level refurbishment is often the only sensible solution.