Airbag control unit with part number A2049010704

What does the airbag control unit A2049010704 do?

In vehicles of the Mercedes-Benz brand, the airbag control unit A2049010704 is the central electronics of the restraint system (SRS). It evaluates the signals from the crash sensors, decides in an accident whether airbags and seatbelt pretensioners are triggered, and monitors the system continuously.

It indicates detected faults via the airbag warning light. After an accident it stores crash data and locks itself.

Why does the control unit A2049010704 fail?

The most common cause is stored crash data after an accident, even if no airbag was triggered; a normal diagnostic tool cannot erase it. Other causes are also possible.

Crash data is one of the entries that a standard tool does not remove.

• aged electronic components
• cold solder joints
• moisture and corrosion on plug connections
• voltage spikes, for example from a weak battery or jump-starting

How can you tell that the A2049010704 is defective?

The airbag warning light in the instrument cluster lights up constantly or intermittently, and an error message appears as well. In addition there is no connection to the diagnostic tool and a fault memory that cannot be cleared; in a crash, the airbags and seatbelt pretensioners may then fail to trigger.

The warning light is one of the most important warning signs, because it indicates a detected fault directly. If it stays on after switching on the ignition, there is a fault.

Which vehicles is the A2049010704 fitted in?

The control unit A2049010704 is fitted in these vehicles: Mercedes-Benz C-Class S204 Estate (2007-2014), W204 Saloon (2007-2014) and C204 Coupé (2011-2015).

The following models are on record for the part number:

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

Matching the part number on the label of the removed unit with this page only confirms that it is the right unit. Have the fault memory read out beforehand; only this result shows whether the control unit itself is at fault or a connector or cable is the cause.

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 A2049010704 work?

First have the fault memory read out and attach the log, then disconnect the battery and remove the control unit. Next, create a repair order online and send in the well-packed unit. At Airbag24, checking, repairing and testing usually takes 3–4 working days.

The sequence is mandatory for safety reasons; removal takes place only after the battery has been disconnected.

At Airbag24 the unit is checked on the test bench, defective components are replaced, crash data is erased and the unit is function-tested. 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 A2049010704 get to Airbag24?

You send the control unit A2049010704 in as a parcel, or you book a UPS collection for an extra charge, and after the repair Airbag24 returns it by UPS.

The printed repair order goes into the parcel, and the unit is packed shock-proof.