Airbag control unit with part number A9079017900

What is the function of the airbag control unit A9079017900?

The airbag control unit A9079017900 is the central safety module in various Mercedes-Benz Sprinter models. Its primary task is to monitor and control all occupant restraint systems. In the event of a crash, it processes data from the crash sensors and coordinates the deployment of airbags and seatbelt pretensioners to provide optimal protection for occupants.

Technically speaking, this module serves as the brain of the passive safety system. It ensures that the appropriate restraint devices are deployed at the right time and with the correct intensity. This precise control is crucial for the overall effectiveness of the airbag system.

In the Mercedes-Benz Sprinter of the W907 series, the control unit is typically installed in a protected location, often beneath the center console or under one of the front seats. This positioning safeguards the sensitive electronics from external influences.

For workshops, it’s important to note that this control unit is also known under the alternative OE numbers 0285015024, A9079000304, and A9079004105. These numbers are technically compatible and refer to the same component.

Why does the control unit A9079017900 fail?

The most common reason for failure of the control unit A9079017900 is the storage of crash data after an accident. Once the module has deployed the restraint systems, it is internally locked for safety reasons. This condition is recorded as a permanent, non-erasable fault in the memory, making professional repair essential.

This lockout is a manufacturer‑specified safety feature designed to prevent a potentially damaged control unit from being reused after an accident. As a result, the module is classified as defective, even though its hardware components are often still intact.

An attempt to clear this fault using a standard diagnostic tool will fail. The crash data is deeply embedded in the module’s internal memory and can only be removed through specialized electronic repair at the component level.

How do you recognize a defect in the A9079017900?

The clearest indication of a faulty airbag control unit A9079017900 is the permanently illuminated airbag warning light on the instrument cluster. Additionally, the vehicle’s diagnostic system reports an internal fault in the control unit that cannot be cleared. In this state, the entire safety system is disabled.

The airbag warning light does not turn off after starting the vehicle. This signals a critical system error to the driver and indicates that the airbags and seatbelt pretensioners would not deploy in another collision.

When diagnosing via the OBD interface, a specific error code is displayed, indicating “crash data stored” or “internal control unit fault.” This entry is permanent and prevents normal operation of the module.

A vehicle with an active airbag warning light will not pass a valid main inspection (HU). Therefore, repairing the control unit is mandatory to restore roadworthiness and the vehicle’s operating permit.

In which vehicles is the A9079017900 installed?

The airbag control unit A9079017900 is exclusively used in the Mercedes-Benz Sprinter platform. It is installed in the newer W907 and W910 generations, as well as in various versions of the predecessor model W906, including 3‑ton, 3.5‑ton, and 5‑ton variants as vans or buses.

At Airbag24, we repair the A9079017900 control unit for the following specific Mercedes-Benz models:

Mercedes-Benz Sprinter W907 (from model year 2018 onward)

Mercedes-Benz Sprinter W910

Mercedes-Benz Sprinter W906 (3.5‑ton bus, 3.5‑ton van, 5‑ton van, 3‑ton van)

Our repair expertise also covers the identical part numbers 0285015024, A9079000304, and A9079004105, which may be fitted in the aforementioned Sprinter models.

How is the A9079017900 repaired?

Repair of the A9079017900 focuses on professional electronic restoration by resetting the stored crash data. After removal and shipment to Airbag24, technicians access the internal memory to safely and completely remove the lockout. The module is then fully functional again and ready for installation.

The process begins in the workshop with the proper removal of the control unit. The module is then securely packaged and sent for repair. A preliminary diagnosis to confirm the fault pattern (stored crash data) is recommended.

At Airbag24, the control unit first undergoes an incoming inspection. This is followed by highly specialized intervention, during which the relevant memory areas on the chip are rewritten. This procedure restores the module to its original factory condition.

After successful repair, the control unit is fully operational again. It can be reinstalled in the vehicle without any additional coding or programming (plug-and-play). All repairs are covered by 2 years' statutory liability for defects.