Airbag control unit with part number 550776300

What is the function of Airbag Control Unit 550776300?

The airbag control unit with part number 550776300 is an original control module manufactured by Autoliv for the occupant safety system (SRS). It is specifically designed for models such as the Citroën Xsara I and Xsara Picasso I, and based on sensor data, it controls the deployment of airbags and seatbelt pretensioners in the event of a crash.

As the central brain of the safety system, this control unit continuously processes information from acceleration and crash sensors in the vehicle. In an emergency, it sends critical ignition signals to the pyrotechnic charges of the airbags and seatbelt pretensioners within milliseconds, providing optimal protection for occupants.

The unit is also alternatively listed under the Citroën part number 9632167780. Proper functionality is essential for vehicle safety, as a malfunction could cause the entire restraint system to fail.

Why does control unit 550776300 fail?

Defects in control unit 550776300 manifest through specific fault codes. Common causes include internal component failures (B1000), issues with the power supply (B1201) due to faulty cables or fuses, and software errors (B1300) resulting from damaged internal data or incorrect coding (B1401).

A frequent fault code is B1000, indicating a general internal defect within the control unit. The exact cause must be analyzed at the chip level.

Fault code B1201 points to a faulty or interrupted power supply. The root cause is often external—such as a broken cable, a defective fuse, or problems with the vehicle battery—but may also require internal repair of the unit itself.

Software-related errors like B1300 (software fault in the control unit) or B1401 (incorrect coding) occur when the internal software is damaged. In these cases, reprogramming or targeted restoration of the software structure is necessary.

Given the variety of engine configurations in the Citroën Xsara I, compatibility is crucial. Alternative part numbers exist, such as 9633504180, 550741100 (gasoline), or 9633621380 and 550535300 (diesel). Exact matching of the part number is mandatory for successful repair or replacement.

How can you recognize a defect in control unit 550776300?

The most obvious sign of a defect in airbag control unit 550776300 is the airbag warning light that remains illuminated in the instrument cluster. Additionally, diagnostic tools may fail to establish communication with the control unit or only detect intermittent connectivity, while reading out specific fault codes.

The airbag warning light that does not turn off after starting the vehicle directly indicates a system malfunction. This alerts the driver that the occupant safety systems might not function correctly in an emergency.

In a specialized workshop, the fault memory can be read out. Typical fault codes such as B1000 (control unit failure), B1201 (power supply issue), B1300 (software error), or B1401 (coding error) provide technicians with precise indications of the nature of the defect and confirm the problem within the control unit itself.

In which models is control unit 550776300 installed?

Airbag control unit 550776300 is primarily used in vehicles of the Citroën brand. At Airbag24, we repair this control module for the Citroën Xsara I and Citroën Xsara Picasso I series, including all facelift models of these generations.

Our technical expertise covers repairs for the following specific vehicle series:

Citroën: Xsara I (model years 1997–2000) as well as the facelift model (2000–2006)

Citroën: Xsara Picasso I (model years 1998–2004) along with the facelift model (2004–2010)

How is control unit 550776300 professionally repaired?

After being sent to Airbag24, control unit 550776300 undergoes a precise diagnosis to verify the reported fault. Depending on the nature of the issue, defective components are replaced, the internal software is reprogrammed, or the power supply is restored. Following successful repair, full functionality is rigorously tested.

The repair process begins with reading out the internal fault memory to confirm codes such as B1000, B1201, B1300, or B1401. This is followed by an analysis of the electronics at the circuit board level.

In cases of software errors (B1300, B1401), our technicians professionally restore and reload the control unit’s data set. For power supply issues (B1201), the relevant electronic components on the circuit board are repaired or replaced.

Upon completion of the repair, the control unit undergoes comprehensive testing to ensure it functions like new. We provide 2 years' statutory liability for defects on every repair performed.