Airbag control unit with part number A9079017804

What is the function of the airbag control unit A9079017804?

The airbag control unit A9079017804 is the central control module for the passive safety system (SRS) in the Mercedes-Benz Sprinter W907. It analyzes data from crash sensors and, in the event of an accident, determines whether and which restraint systems—such as airbags and seatbelt pretensioners—should be deployed to protect occupants.

As the brain of the Supplemental Restraint System (SRS), this module continuously processes information from acceleration and pressure sensors distributed throughout the vehicle. Its primary task is to accurately detect a crash situation and activate the appropriate safety measures with lightning speed.

The proper functioning of this control unit is essential for vehicle safety, as a failure can disable the entire airbag system.

Why does the control unit A9079017804 fail?

The most common cause of failure for the control unit A9079017804 is the storage of crash data after an accident, which locks the module. Other causes include internal electronic faults leading to communication failures, and, more rarely, moisture damage to the circuit board.

Even after a minor rear-end collision or just the deployment of seatbelt pretensioners, the control unit irrevocably stores crash data. This safety measure locks the module to prevent further use, indicated by a permanently illuminated airbag warning light.

Another frequent issue is internal electronic malfunctions. Components on the circuit board may fail, resulting in communication problems with diagnostic tools or persistent error codes that cannot be cleared, despite all external components like airbags and sensors remaining intact.

This fault pattern applies not only to part number A9079017804 but also to related variants such as A9079017900, A9079000304, A9079004105, and A9079004305, installed in Sprinter W906/W907 or Vito W639 models.

How do you recognize a defect in A9079017804?

A defective airbag control unit A9079017804 is primarily signaled by the persistently illuminated airbag warning light in the cockpit. Additionally, diagnostic tools may lose communication with the SRS module, or specific, non‑erasable error codes may appear.

The most obvious symptom is the active airbag warning light that fails to turn off after starting the vehicle. This is a clear indication of a serious malfunction in the restraint system.

Workshops often find that the control unit is no longer responsive. Attempts to read out error codes fail because no connection can be established via the OBD interface.

Furthermore, specific error messages such as “fuel shut-off valve defective” or issues related to the driver’s airbag or seatbelt pretensioners may be stored in the fault memory, pointing to an internal defect within the control unit.

In which vehicles is the control unit A9079017804 installed?

The airbag control unit with part number A9079017804 is specific to the Mercedes-Benz Sprinter model series W907, produced since 2018. Similar—and partially interchangeable—control units are also found in earlier models such as the Sprinter W906 or the Vito W639.

At Airbag24, we repair this control unit for the following main model:

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

It is mainly used in van variants, often paired with diesel engines, rear-wheel drive, ABS, and start-stop systems. Repairs are also available for related part numbers such as A9079017900, A9079004105, and others from the same family.

How is A9079017804 professionally repaired?

Professional repair is provided as a shipping service. Following an initial analysis at Airbag24, stored crash data is erased at the hardware level, and any defective electronic components are replaced. Final tests ensure full functionality, avoiding the need for an expensive new purchase.

Before removing the control unit, a specialized workshop should first read out the error codes. The diagnostic report assists technicians in targeted troubleshooting and should be included with the package. After sending the unit to Airbag24, it undergoes a proven repair process.

First, the module is subjected to a thorough analysis to confirm the root cause of the fault. Next, stored crash data is deleted, and the hardware lock is released. If additional electronic defects are present, the affected components on the circuit board are expertly repaired.

Following repair, the control unit is comprehensively tested to ensure flawless communication and operation. You receive 2 years' statutory liability for defects on the repair. This process is significantly more cost-effective than purchasing a new part, which typically costs between €190 and €227.