Airbag control unit with part number 985104265R

What does the airbag control unit 985104265R do?

The airbag control unit 985104265R is the central control unit of the restraint system (SRS) for Smart. It evaluates the signals from the crash sensors and decides within milliseconds in an accident whether the airbags and seatbelt pretensioners are triggered.

The unit belongs to the restraint system, which is designed to protect the occupants in an accident. It runs along while you drive and checks the system continuously.

It shows faults via the airbag warning light in the instrument cluster. After an accident it stores crash data and locks itself; both affect the control unit itself.

Why does the control unit 985104265R fail?

Stored crash data is the most common cause, even if no airbag was triggered in the accident. Other causes are aged electronic components, cold solder joints, moisture and corrosion on plug connections, and voltage spikes, for example from a weak battery or jump-starting.

A normal diagnostic tool cannot erase the crash data. During the repair, Airbag24 removes it.

The other causes concern the electronics in general. Components age, solder joints can go cold, and moisture or corrosion affect plug connections. Voltage spikes also act on the electronics.

How can you tell that the 985104265R is defective?

A defect in the airbag control unit 985104265R shows up as the airbag warning light in the instrument cluster, as fault messages, as a diagnostic tool with no connection and as a fault memory that cannot be cleared.

The airbag warning light stays on permanently or comes on intermittently. Fault messages in the instrument cluster are a further sign.

In the worst case, the airbags and seatbelt pretensioners may not deploy. Have the system checked promptly once the warning light comes on.

Which vehicles is the 985104265R fitted in?

The control unit 985104265R is fitted in these vehicles: Smart Fortwo C453 (2014-2024).

The following overview lists the vehicles for this part number:

• Smart Fortwo C453 (2014-2024)

Compare the part number on the label of the removed unit with this page, as this only confirms that it is the right unit. Also have the fault memory read out before you remove anything. Only the result shows whether the control unit is defective or whether a plug or a cable is the cause.

For the same vehicles, we also repair control units with the part numbers A453 901 89 00, A4539001702, A4539017400.

How does the repair of the 985104265R work?

First read out the fault memory and enclose the log. Then disconnect the battery and only after that remove the control unit 985104265R. Next, create a repair order online and send the unit in well packed. Airbag24 usually checks, repairs and tests the unit within 3–4 working days.

Airbag24 checks the unit on the test bench, replaces defective components and erases the stored crash data. A function test follows.

The 3–4 working days apply only to this work at Airbag24. After that, 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 985104265R get to Airbag24?

You send the control unit 985104265R 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 shock-proof.