Airbag control unit with part number A2139007320

What does the airbag control unit A2139007320 do?

The airbag control unit A2139007320 is the central control unit of the restraint system for Mercedes-Benz. It evaluates the crash sensors, decides in an accident within fractions of a second whether airbags and seatbelt pretensioners are triggered, and monitors the system continuously. It reports faults via the airbag warning light.

The evaluation runs without interruption, and the measured values feed continuously into the decision.

After an accident, the unit stores crash data and locks itself. A reported fault therefore calls for a prompt check.

Why does the control unit A2139007320 fail?

Stored crash data after an accident is the most common cause, even if no airbag has deployed; a standard diagnostic tool cannot erase it. Other causes are ageing electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes.

The crash data remains stored after an accident, even if the restraint devices were not triggered. A standard diagnostic tool cannot be made to remove it, so the entry stays in the fault memory.

Electronic components age, and solder joints can go cold. Moisture and corrosion at plug connections disturb the contact, and voltage spikes in the vehicle electrical system, for example with a weak battery or a jump start, put strain on the electronics. The inspection shows which cause is present.

How can you tell that the A2139007320 is defective?

Defects on the A2139007320 show up in several places: the airbag warning light in the instrument cluster lights up permanently or intermittently, a fault message appears in the instrument cluster, the diagnostic tool finds no connection, and the fault memory cannot be cleared.

Typical signs are:

• airbag warning light permanently or intermittently on
• fault message in the instrument cluster
• diagnostic tool without connection to the control unit
• fault memory cannot be cleared

With these signs, airbags and seatbelt pretensioners may not trigger in an emergency. This applies regardless of how inconspicuous the vehicle seems in everyday use.

Which vehicles is the A2139007320 fitted in?

The control unit A2139007320 is fitted in these vehicles: Mercedes-Benz E-Class S213 Estate (2016-2023) and W213 Saloon (2016-2023).

The fitment covers these models:

• 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, as this only confirms that you have the correct unit. Also have the fault memory read out beforehand, because only the log shows whether the control unit is defective or whether a plug or a 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 A2139007320 work?

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

Airbag24 checks the unit on the test bench, repairs defective components, erases the stored crash data and carries out a function test. 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 A2139007320 get to Airbag24?

You send the control unit A2139007320 as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 returns it by UPS.

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