Airbag control unit with part number 550538400

What does the airbag control unit 550538400 do?

The airbag control unit 550538400 takes over control of the SRS system in Peugeot vehicles. The crash sensors supply it with measurements, and from these it selects, within milliseconds of a crash, the airbags and seatbelt pretensioners to fire.

During operation it monitors the system continuously. It indicates faults via the airbag warning light in the instrument cluster.

After a crash it stores crash data and locks itself.

Why does the control unit 550538400 fail?

The most common cause is crash data stored after an accident, even without a deployed airbag. It cannot be erased with a standard diagnostic tool.

Other causes include aged electronic components and cold solder joints, which can make themselves felt gradually.

Moisture and corrosion on plug connections, along with voltage spikes, for example from a weak battery or jump-starting, round off the picture.

How can you tell that the 550538400 is defective?

The main signs of a defect in the 550538400 are the airbag warning light in the instrument cluster and messages on the display.

• Airbag warning light stays on permanently or intermittently
• Fault message in the instrument cluster
• Diagnostic tool gets no connection to the control unit
• Fault memory cannot be cleared

In an emergency, airbags and seatbelt pretensioners may fail to deploy if the unit has problems. The light is the sign that the control unit itself is reporting a fault.

The warning should therefore be looked into promptly.

Which vehicles is the 550538400 fitted in?

The 550538400 is fitted in these vehicles: Peugeot 106 S2 (1996-2003) and S1 (1991-1996).

The list of associated vehicles follows.

• Peugeot 106 S2 (1996-2003)
• Peugeot 106 S1 (1991-1996)

Comparing the part number on the label of the removed unit with this page ensures that you have the correct unit. Whether the control unit is defective or a plug or cable is the cause is answered by the fault memory. Please have it read out beforehand.

For the same vehicles, we also repair control units with the part numbers 550404200, 550579000, 550747400, 550790400, 550892800, 654779.

How does the repair of the 550538400 work?

First have the fault memory read out and attach the log, then disconnect the battery. Only then remove the control unit. Processing at Airbag24 normally takes 3–4 working days.

The sequence follows safety requirements and is binding. Only then create a repair order online and pack the unit well.

At Airbag24 the unit is tested, defective components are repaired, stored crash data is erased and a function test is run. Your own unit is returned to you afterwards.

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 550538400 get to Airbag24?

You can send a parcel yourself, or book a UPS collection for the 550538400 for an extra charge. Airbag24 sends the control unit back to you by UPS after the repair.

Enclose the printed repair order with the parcel, and pack the unit shock-resistant.