Airbag control unit with part number A2059004708

What does the airbag control unit A2059004708 do?

The airbag control unit A2059004708 is the central control unit of the restraint system (SRS) for Mercedes-Benz. It processes the readings from the crash sensors and, in an accident, decides within milliseconds which airbags and seatbelt pretensioners are triggered. It monitors the system continuously and reports faults via the airbag warning light.

In operation, the control unit checks the sensors, the triggering units and the wiring between them. Only when all parts of the system work together can it activate the right restraint devices in an emergency.

After an accident, the unit stores crash data and locks itself. Beyond this storage, nothing more belongs to the functional description, but it is the reason why a unit belongs in repair after an accident.

Why does the control unit A2059004708 fail?

The most common cause at the A2059004708 is crash data stored after an accident, even if no airbag fired; it cannot be erased with a normal diagnostic tool. Other causes include aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes from a weak battery or jump-starting.

Crash data is the most obvious explanation if the unit becomes conspicuous after an accident. It is not the only possibility, though, and the other causes act even without any accident.

Ageing, moisture and voltage fluctuations attack electronics and plug connections. Which cause applies is shown only by inspecting the unit.

How can you tell that the A2059004708 is defective?

A defect in the A2059004708 shows itself through several signs in the instrument cluster and on the diagnostic tool. In an emergency, the airbags and seatbelt pretensioners may then fail to deploy.

• The airbag warning light in the instrument cluster stays on permanently or intermittently.
• A fault message appears in the instrument cluster.
• The diagnostic tool receives no connection to the control unit.
• The fault memory cannot be cleared.

A single indication does not prove any damage, but it is the reason to have the fault memory read out.

Which vehicles is the A2059004708 fitted in?

For Mercedes-Benz, the assignment is recorded on this page. The control unit A2059004708 is fitted in these vehicles: Mercedes-Benz C-Class W205 Saloon (2014-2021) and S205 Estate (2014-2021).

The vehicles in detail:

• Mercedes-Benz C-Class W205 Saloon (2014-2021)
• Mercedes-Benz C-Class S205 Estate (2014-2021)

Compare the part number on the label of the removed unit with this page, because that only ensures that it is the right unit. Have the fault memory read out beforehand, since only that result shows whether the control unit is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers A 205 900 21 41, A205 900 18 14, A205 900 63 37, A205 900 95 27, A2059002512, A2059008618.

How does the repair of the A2059004708 work?

First have the fault memory read out and enclose the log, then disconnect the battery and only then remove the control unit. Next, create a repair order online and send in the packed unit. Checking, repairing and testing at Airbag24 usually take 3–4 working days, after which your own unit is returned.

Airbag24 checks the unit, replaces defective components, erases stored crash data and carries out a function test.

The order is binding, because disconnecting the battery before removal ensures safety when working on the system.

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 A2059004708 get to Airbag24?

You send the control unit A2059004708 in as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 returns it to you by UPS.

Put the printed repair order in the parcel, and pack the unit shockproof.