Airbag control unit with part number A2129018608

What does the airbag control unit A2129018608 do?

The airbag control unit A2129018608 controls the restraint system (SRS) of vehicles of the make Mercedes-Benz as a central unit. It evaluates the crash sensors, determines within milliseconds in an accident the triggering of airbags and seatbelt pretensioners, and monitors the system continuously.

It indicates faults via the airbag warning light in the instrument cluster. After an accident the unit stores crash data and locks itself.

The control unit thus forms the link between sensors and airbags.

Why does the control unit A2129018608 fail?

Stored crash data is the most common cause, even if no airbag has deployed in an accident. A standard diagnostic tool cannot erase it. Aged components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes are also possible.

The storage of these entries in the unit ends with the repair.

The other causes concern ageing, moisture and the power supply. A failure can thus be connected with a weak battery or a jump start.

How can you tell that the A2129018608 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently, and an error message appears in the instrument cluster. In addition, the diagnostic tool does not reach the control unit, and the fault memory cannot be cleared. In an emergency, airbags and seatbelt pretensioners may then fail to deploy.

A defect is therefore not presumed but indicated by the light.

What the cause is only the read-out of the fault memory will clarify.

Which vehicles is the A2129018608 fitted in?

The information applies to the control unit A2129018608. It is fitted at Mercedes-Benz in these vehicles: Mercedes-Benz E-Class S212 Estate (2009-2016), W212 Saloon (2009-2016) and W212 Saloon Facelift (2013-2016).

The individual vehicles are listed here:

• Mercedes-Benz E-Class S212 Estate (2009-2016)
• Mercedes-Benz E-Class W212 Saloon (2009-2016)
• Mercedes-Benz E-Class W212 Saloon Facelift (2013-2016)

Whether the label on the removed unit matches this page only says something about the right unit. Have the fault memory read out in advance; the log 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 2129011105, A212 901 42 04, A212 901 85 08, A2128603002, A2129010700.

How does the repair of the A2129018608 work?

Above all, have the fault memory read out and enclose the log, then disconnect the battery. Only then remove the control unit and create a repair order online. Processing at Airbag24 usually takes 3–4 working days.

On a test bench, Airbag24 examines the unit. If needed, components are replaced, crash data removed and a function test run before the unit goes back to you.

Nothing may be swapped before removal, because the order of steps serves safety.

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 A2129018608 get to Airbag24?

You send us the unit as a parcel, or you book a UPS collection for an extra charge. After the repair, the unit comes back to you by UPS.

The printed repair order lies in the carton, and the control unit is packed shock-proof.