Airbag control unit with part number A2079011900

What does the airbag control unit A2079011900 do?

The A2079011900 forms the control centre of the restraint system (SRS) at Mercedes-Benz. It evaluates the crash sensors, selects the appropriate airbags and seatbelt pretensioners within milliseconds in an accident, and reports faults via the airbag warning light.

Monitoring runs continuously. If the unit detects a deviation, it records it and displays it.

After an accident, crash data are stored in the unit, and the unit locks itself as a result.

Why does the control unit A2079011900 fail?

The most widespread cause is crash data that remain stored in the unit after an accident, even if no airbag has fired. An ordinary diagnostic tool does not erase them; Airbag24 removes them during the repair of the A2079011900.

What is decisive is that the storage is not tied to an airbag having fired. The unit documents the event, and the entries remain as long as no one removes them.

Further causes that generally come into consideration:

• Aged components in the electronics
• Cold solder joints on the circuit board
• Moisture and corrosion at plug connectors
• Voltage spikes, for example from a weak battery or a jump start

Which of these causes applies is shown only by the examination on the test bench, not by guesswork.

How can you tell that the A2079011900 is defective?

The airbag warning light in the instrument cluster stays on permanently or intermittently. Accompanying this, error messages appear in the instrument cluster, the diagnostic tool cannot reach the control unit, or the fault memory cannot be erased. In this state, airbags and seatbelt pretensioners on the A2079011900 may not be able to trigger in an emergency.

The signs occur in different combinations depending on their severity. Even a single one of them should be checked promptly, because the entire restraint system may be affected.

Follow up on such notices rather than trusting that they will disappear on their own.

Which vehicles is the A2079011900 fitted in?

The A2079011900 is installed in these vehicles: Mercedes-Benz E-Class C207 Coupé (2009-2016) and A207 Convertible (2010-2017).

The overview lists the vehicles known to us for this part number.

• Mercedes-Benz E-Class C207 Coupé (2009-2016)
• Mercedes-Benz E-Class A207 Convertible (2010-2017)

Have the fault memory read out before removal. A look at it shows whether the control unit itself is the cause. Afterwards compare the part number on the removed unit with this page.

For the same vehicles, we also repair control units with the part numbers 2079011700, A2078203226, A2079010100, A212 901 85 08.

How does the repair of the A2079011900 work?

The fault memory is read out before removal, after which you remove the A2079011900 and create a repair order online. At Airbag24, processing of the A2079011900 usually takes 3–4 working days.

Before removal, have the log ready and disconnect the battery. Then take the control unit out and send it in.

At Airbag24 the unit is examined on the test bench, defective components are replaced and the crash data are erased. A function test completes the work. The stated time covers only these steps.

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 A2079011900 get to Airbag24?

You send the control unit A2079011900 to Airbag24 as a parcel, or you book a UPS collection for an extra charge. After the repair, you receive your own unit back by UPS.

Print the repair order and put it in the parcel. Pack the unit so that it is protected against shocks.