Airbag control unit with part number A2139007005

What does the airbag control unit A2139007005 do?

The airbag control unit A2139007005 is the central control unit of the restraint system (SRS) for Mercedes-Benz. It evaluates the signals from the crash sensors and decides in the event of an accident which airbags and seatbelt pretensioners are triggered. After an accident it stores crash data and locks itself.

The unit keeps the entire restraint system under observation. It continuously checks the sensors, the firing circuits and the connections to the restraint devices.

It stores faults in the fault memory and shows them via the airbag warning light in the instrument cluster. Only the repair lifts the lock after an accident.

Why does the control unit A2139007005 fail?

The most common cause is crash data stored after an accident, even if no airbag was deployed. A normal diagnostic tool cannot erase it. Other causes are aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage peaks.

The fact that crash data can be erased means for you: Airbag24 removes it during the repair. Until then it stays stored in the unit.

Aged electronic components lose reliability over time, and cold solder joints can crack. Moisture and corrosion affect the plug connections, while voltage peaks occur, for example, with a weak battery.

The inspection will show which of these causes applies to your unit.

How can you tell that the A2139007005 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently, an error message appears in the instrument cluster, the diagnostic tool gets no connection to the control unit, and the fault memory cannot be cleared.

The airbag warning light is the most important sign. If it lights up permanently or intermittently, the restraint system has detected a fault. An error message in the instrument cluster may also appear.

If no connection to the control unit can be established and the fault memory cannot be cleared, the control unit itself may be affected. In that case airbags and seatbelt pretensioners may not be able to trigger in an emergency. Please have the finding checked promptly.

Which vehicles is the A2139007005 fitted in?

The control unit A2139007005 is fitted in these vehicles: Mercedes-Benz E-Class S213 Estate (2016-2023) and W213 Saloon (2016-2023).

We know of the following vehicles for this part number:

• Mercedes-Benz E-Class S213 Estate (2016-2023)
• Mercedes-Benz E-Class W213 Saloon (2016-2023)

Compare the part number on the label of the removed unit with this page. This only confirms that it is the correct unit. Before that, have the fault memory read out, because only this result shows whether the control unit or a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers A213 900 46 25, A213 900 88 22, A213 900 88 28, A2139007105, A2139010104.

How does the repair of the A2139007005 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 the unit in well packed. Airbag24 usually needs 3–4 working days for testing, repairing and checking.

This sequence is binding, because it ensures safety during removal. The battery is disconnected only after the log is available.

At Airbag24 the unit is examined on the test bench. Defective components are repaired, the crash data is erased and a function test is carried out. Afterwards your own unit is 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 A2139007005 get to Airbag24?

You send the control unit A2139007005 as a parcel, or you book a UPS collection for an extra charge. After the repair Airbag24 returns it to you by UPS.

The printed repair order goes into the parcel. Pack the unit shockproof so that it arrives undamaged.