Airbag control unit with part number A2049013203

What does the airbag control unit A2049013203 do?

The airbag control unit A2049013203 brings the evaluation together within the restraint system (SRS) of Mercedes-Benz. From the signals of the crash sensors it determines which airbags and seatbelt pretensioners are to be triggered in an impact, and it continuously checks the state of the system. Detected faults are shown via the airbag warning light.

After an accident the unit secures crash data and then locks itself.

A control unit of this kind works without any operation of its own and remains largely invisible to the driver.

Why does the control unit A2049013203 fail?

Stored crash data is the most common cause: it remains in the unit after an accident, even if no airbag deployed, and a normal diagnostic tool does not remove it. Added to this are aged components, cold solder joints, moisture and corrosion at plug connections, as well as voltage spikes.

The other causes develop over time, for example when components age or moisture causes corrosion on a plug. Voltage spikes from a jump start or a weak battery also belong to this group.

How can you tell that the A2049013203 is defective?

A defect becomes apparent when the airbag warning light stays on permanently or intermittently, an error message appears in the instrument cluster, the diagnostic tool cannot establish contact with the control unit, or the fault memory cannot be cleared. In an emergency, airbags and seatbelt pretensioners may then fail to deploy.

• Airbag warning light on permanently or intermittently
• Error message in the instrument cluster
• No connection between diagnostic tool and control unit
• Fault memory cannot be cleared

The light indicates the condition; a check is then the right next step.

Which vehicles is the A2049013203 fitted in?

The A2049013203 is fitted in these vehicles: Mercedes-Benz C-Class S204 Estate (2007-2014), W204 Saloon (2007-2014) and C204 Coupé (2011-2015).

The list by vehicle type:

• Mercedes-Benz C-Class S204 Estate (2007-2014)
• Mercedes-Benz C-Class W204 Saloon (2007-2014)
• Mercedes-Benz C-Class C204 Coupé (2011-2015)

Compare the part number on the label of the removed unit with this page. This only clarifies whether it is the correct unit. Whether the control unit itself is defective or whether a plug or cable is the cause is shown only by reading out the fault memory, which you arrange beforehand.

For the same vehicles, we also repair control units with the part numbers 2048709426, 5WK44740, A204 870 68 26, A204 901 26 04, A204 901 35 02, A2048208285.

How does the repair of the A2049013203 work?

The order is binding: first you read out the fault memory, enclose the log and disconnect the battery; only then do you remove the A2049013203. Next you create a repair order online and send the unit well packed. Airbag24 checks it, replaces defective components, deletes crash data and carries out a function test; for this Airbag24 generally needs 3–4 working days.

Your own unit is returned to you once this work is complete.

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 A2049013203 get to Airbag24?

You send the unit as a parcel or have it collected by UPS for an extra charge. After the repair it goes back to you by UPS.

Pack the control unit so that it is shock-resistant and enclose the printed repair order.