Airbag control unit with part number A2049016800

What does the airbag control unit A2049016800 do?

The unit A2049016800 controls the restraint system (SRS) of Mercedes-Benz. Based on the signals from the crash sensors, it determines in a crash within milliseconds which airbags and seatbelt pretensioners are triggered. After an accident it stores crash data and locks itself.

The control unit monitors the entire system continuously. If it detects a fault, it reports this via the airbag warning light in the instrument cluster.

The crash data belong to the memory of the control unit and are important for diagnosis.

Why does the control unit A2049016800 fail?

The most common cause is crash data from an earlier accident, even if no airbag triggered; a normal diagnostic tool cannot erase it. Beyond that, general causes come into consideration.

The erasure of the crash data is therefore a firm part of the repair at Airbag24.

The other causes at a glance:

• Aged electronic components
• Cold solder joints
• Moisture and corrosion on plug connections
• Voltage spikes, for example from a weak battery or a jump start

How can you tell that the A2049016800 is defective?

Typical signs are an airbag warning light in the instrument cluster that lights up permanently or intermittently, an error message, a missing connection to the diagnostic tool and a fault memory that cannot be cleared. Airbags and seatbelt pretensioners may then not trigger in an emergency.

• The airbag warning light lights up permanently
• The airbag warning light lights up only intermittently
• Error message in the instrument cluster
• The diagnostic tool cannot find the control unit
• The fault memory cannot be cleared

A picture like this is a warning that you should take seriously before you start removing the unit.

Which vehicles is the A2049016800 fitted in?

The A2049016800 is fitted in these vehicles: Mercedes-Benz C-Class S204 Estate (2007-2014), W204 Saloon (2007-2014) and C204 Coupé (2011-2015). The details are based on the data we hold for this control unit.

The models are listed in the following list:

• 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 your removed unit with this page. That confirms that you have the right control unit. Have the fault memory read out beforehand, because only this log shows whether the control unit itself is defective or whether a plug 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 A2049016800 work?

First you have the fault memory read out, enclose the log, and disconnect the battery. Only after that do you remove the unit, create a repair order online and send in the device. Processing at Airbag24 usually takes 3–4 working days.

The unit is then checked on the test bench, defective components are replaced, the stored crash data are erased and a function test is carried out. Afterwards your own unit comes back 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 A2049016800 get to Airbag24?

You either send the unit as a parcel or book a UPS collection for an extra charge. The return after the repair is made by UPS.

Make sure the printed repair order is in the parcel and the control unit is packed shockproof.