Airbag control unit with part number 550893100

What does the airbag control unit 550893100 do?

The airbag control unit 550893100 is the central control unit for the SRS in Citroën vehicles. In a collision it decides within milliseconds which airbags and seatbelt pretensioners are triggered, relying on signals from the crash sensors. It monitors the system continuously and shows faults via the airbag warning light.

The control unit is connected to all sensors and firing circuits. This allows it to detect faults before they matter in an emergency.

After an accident it stores crash data and locks itself.

Why does the control unit 550893100 fail?

The most common cause is crash data from an accident that remains stored in the unit, even if no airbag was triggered. A normal diagnostic tool does not remove it. In addition there are ageing electronic components, cold solder joints, moisture and corrosion on plug connectors, and voltage spikes.

Crash data is inconspicuous, because the car can keep driving normally after the incident.

Electronics age, and solder joints can go cold. Moisture and corrosion attack the plug connectors, which carry the signals.

Voltage spikes, for example from a weak battery or a jump start, put strain on the circuit. Airbag24 deletes the crash data during the repair.

How can you tell that the 550893100 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently as soon as there is a fault in the 550893100. The instrument cluster also shows an error message, and the diagnostic tool cannot find the control unit. If the fault memory cannot be cleared, an inspection is necessary. In an emergency, the airbags and seatbelt pretensioners may fail to deploy.

This warning light is one of the system's direct feedback signals. It shows that something is wrong in the restraint system.

A connection problem with the diagnostic tool is handled in the same way: it is a finding that needs to be clarified.

Which vehicles is the 550893100 fitted in?

The airbag control unit 550893100 is fitted by Citroën in these vehicles: Citroën Xsara Picasso I (1998-2004) and I Facelift (2004-2010).

The vehicle assignments stored for this part number are listed below.

• Citroën Xsara Picasso I (1998-2004)
• Citroën Xsara Picasso I Facelift (2004-2010)

Compare the part number on the label of the removed unit with this page. This shows that you have the correct unit, but says nothing about the cause. For this reason, have the fault memory read out before removal. Only this shows whether the control unit or a plug or cable is at fault.

For the same vehicles, we also repair control units with the part numbers 550776300, 9632167780, 9652246980.

How does the repair of the 550893100 work?

You have the fault memory read out and the log enclosed. Afterwards you disconnect the battery and remove the control unit 550893100. Then you create the repair order online and pack the unit carefully.

Airbag24 tests the control unit on the test bench, replaces defective components, deletes the crash data and carries out a function test.

The unit is then returned to you. Processing at Airbag24 usually takes 3–4 working days.

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 550893100 get to Airbag24?

You send the control unit 550893100 as a parcel or arrange a UPS collection for an extra charge. Airbag24 sends the unit back by UPS after the repair.

The printed repair order goes into the parcel, and the unit is packed shock-proof.