Airbag control unit with part number A1729015905

What does the airbag control unit A1729015905 do?

The airbag control unit A1729015905 controls the restraint system (SRS) at Mercedes-Benz. It evaluates the signals from the crash sensors, decides in an accident on the triggering of airbags and seatbelt pretensioners, and monitors the system continuously.

Faults in the system are reported by the unit via the airbag warning light. It also checks the connected components during normal driving.

After an accident, the unit stores crash data and locks itself. The lock ends only with the repair.

Why does the control unit A1729015905 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 aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes, for example from a weak battery or a jump start.

Crash data remains in the memory until it is specifically removed. For this reason, the entry stays in the fault memory even if the vehicle otherwise runs without any problems.

Aged components gradually lose reliability. Moisture and corrosion attack the contacts, and cold solder joints can cause contact problems.

Voltage spikes arise, for example, with a weak battery or when starting with a jump start. Such voltages stress the electronics.

How can you tell that the A1729015905 is defective?

A defect shows up as an airbag warning light in the instrument cluster that lights up permanently or intermittently, and as a fault message in the instrument cluster. In addition, there is no connection to the diagnostic tool, and the fault memory cannot be cleared.

Airbags and seatbelt pretensioners may then fail to trigger in an emergency. The warning light indicates the defect and must not be ignored.

If the warning light comes on, have the vehicle checked promptly.

Which vehicles is the A1729015905 fitted in?

The airbag control unit A1729015905 is fitted in these vehicles: Mercedes-Benz SLK-Class R172 Convertible (2011-2016); Mercedes-Benz SLC-Class R172 Convertible (2016-2020).

The vehicles for which this part number is on record can be found here:

• Mercedes-Benz SLK-Class R172 Convertible (2011-2016)
• Mercedes-Benz SLC-Class R172 Convertible (2016-2020)

Have the fault memory read out beforehand, because the result alone shows whether the control unit is defective or whether a plug or cable is the cause. Comparing the label of the removed unit with this page is only done to make sure that it is the right unit.

For the same vehicles, we also repair control units with the part numbers A1729015704, A1729015805, A1729017601, A1729019102.

How does the repair of the A1729015905 work?

First have the fault memory read out and enclose the log. Then disconnect the battery, and only afterwards remove the control unit. Next, create a repair order online, pack the unit well and send it in; processing at Airbag24 usually takes 3–4 working days.

Airbag24 checks the unit on the test bench, replaces defective components, erases the stored crash data and carries out a function test. Your unit then goes 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 A1729015905 get to Airbag24?

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

Put the printed repair order into the parcel and pack the unit shockproof.