Airbag control unit with part number A4479004908

What does the airbag control unit A4479004908 do?

The airbag control unit A4479004908 controls the restraint system (SRS) of Mercedes-Benz. It processes the sensor signals, selects in a crash which airbags and seatbelt pretensioners to trigger, and monitors the entire system. It shows faults via the airbag warning light.

The housing also bears the manufacturer number Bosch 0285013868. It serves for comparison; the part number A4479004908 remains the identifier of this page.

After a crash, the unit stores crash data and locks itself.

Why does the control unit A4479004908 fail?

Most often this is due to crash data stored after an accident, even if no airbag has deployed. Other causes are aged components, cold solder joints, moisture and corrosion on connectors, and voltage spikes.

A standard diagnostic tool cannot erase the crash data; Airbag24 erases them during the repair. After that, the remaining fault diagnosis can be carried out without this legacy burden.

Ageing and environmental influences act on electronics and plug connections over a long time before a fault becomes visible.

How can you tell that the A4479004908 is defective?

Signs of a defect are an airbag warning light that stays on permanently or intermittently, a fault message in the instrument cluster, a diagnostic tool with no connection to the control unit, and a fault memory that cannot be cleared.

• airbag warning light stays on permanently or intermittently
• fault message in the instrument cluster
• no connection between diagnostic tool and control unit
• fault memory cannot be cleared

In that case, airbags and seatbelt pretensioners may not trigger in an emergency. Have such an indication checked promptly.

Which vehicles is the A4479004908 fitted in?

The control unit A4479004908 is fitted in these vehicles: Mercedes-Benz Vito W447 (from 2014); Mercedes-Benz V-Class W447 (from 2014). The label on the removed unit shows the part number, which you use for the comparison.

These vehicles are equipped with the control unit:

• Mercedes-Benz Vito W447 (from 2014)
• Mercedes-Benz V-Class W447 (from 2014)

Compare the part number on the unit's label with this page; this only ensures that it is the correct unit. Have the fault memory read out beforehand, as only it shows whether the control unit is defective or a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 4479006309, A 447 900 10 00, A4479000900, A4479010300.

How does the repair of the A4479004908 work?

First have the fault memory read out and attach the log, then disconnect the battery and remove the control unit. Then create a repair order online and send the unit in well packed. At Airbag24, the inspection, repair and function test usually take 3–4 working days.

Airbag24 checks the unit on the test bench, replaces defective components, erases stored crash data and carries out the 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 A4479004908 get to Airbag24?

You send the control unit as a parcel or book a UPS collection for an extra charge. Airbag24 sends the repaired unit back to you via UPS after the repair.

Put the printed repair order into the parcel and pack the unit shock-resistant.