Airbag control unit with part number A2048709526

What does the airbag control unit A2048709526 do?

The airbag control unit A2048709526 controls the restraint system (SRS) of Mercedes-Benz. It evaluates the crash sensors and determines in the event of an accident which airbags and seatbelt pretensioners are triggered, within milliseconds.

It also monitors the system during operation. It reports faults via the airbag warning light in the instrument cluster.

After an accident it stores crash data and locks itself. Only the repair lifts the lock.

Why does the control unit A2048709526 fail?

The most common cause is crash data stored after an accident, even if no airbag has deployed; a normal diagnostic tool cannot erase it. Other causes are aged electronic components, cold solder joints, moisture and corrosion on plug connectors, and voltage spikes.

Stored crash data is the obvious starting point for the inspection. It remains in the unit until it is erased during the repair.

The other causes relate to ageing and environmental influences. Electronic components change over time, cold solder joints arise during manufacture or through stress, and moisture and corrosion attack the connectors.

Voltage spikes caused by a weak battery or a jump start also affect the electronics.

How can you tell that the A2048709526 is defective?

A defect in the control unit A2048709526 shows itself through the airbag warning light, fault messages in the instrument cluster, a missing connection to the diagnostic tool, or a fault memory that cannot be cleared.

The airbag warning light is the most important signal, because it reflects the state of the restraint system. It lights up constantly or intermittently when a fault is present.

In that case airbags and seatbelt pretensioners may not deploy in an emergency. An inspection is therefore advisable.

Which vehicles is the A2048709526 fitted in?

The control unit A2048709526 is fitted in these vehicles: Mercedes-Benz C-Class S204 Estate (2007-2014), W204 Saloon (2007-2014) and C204 Coupé (2011-2015).

You will find the vehicles this unit is intended for in this 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 the removed unit with this page. This only confirms that it is the correct unit. Have the fault memory read out beforehand. Only 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 2048709426, 5WK44740, A204 870 68 26, A204 901 26 04, A204 901 35 02, A2048208285.

How does the repair of the A2048709526 work?

First have the fault memory read out and attach the log. Then disconnect the battery and only then remove the control unit A2048709526. Next, create a repair order online and send the unit in, well packed.

Airbag24 checks the unit on the test bench, repairs defective components, erases the crash data and carries out a function test. Processing at Airbag24 usually takes 3–4 working days.

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 A2048709526 get to Airbag24?

You send the control unit A2048709526 as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 sends the unit back to you by UPS.

Put the printed repair order into the parcel and pack the unit shock-proof.