Airbag control unit with part number 550539800

What is the function of Airbag Control Unit 550539800?

The Airbag Control Unit 550539800 is the central control module for the occupant protection system in the Peugeot 806 I. Its primary task is to process sensor data and deploy airbags and seatbelt pretensioners in the event of a crash. After a collision, it stores relevant crash data (crash data), which requires professional reset.

This electronic module is safety-critical and continuously monitors all components of the airbag system. It ensures that, in an emergency, a response occurs within seconds to provide optimal protection for vehicle occupants.

Storing crash data is a manufacturer‑specified safety feature. It prevents the reuse of a potentially damaged system without prior inspection and repair.

Why does Control Unit 550539800 fail?

The most common cause of failure for Control Unit 550539800 is the storage of crash data after an accident. This data locks the unit’s functionality and cannot be cleared by standard workshop diagnostic tools. Other causes include general electronic faults in circuit board components, leading to internal malfunctions.

Following a collision, the control unit is locked by the system to prevent further driving with a deployed or faulty safety system. The airbag warning light then remains illuminated, signaling the need for action.

In addition to crash‑data lockout, age‑related failures of electronic components on the circuit board can also occur. These result in similar symptoms, such as persistent fault codes or a lit warning light—even without an accident.

The same fault patterns are also observed with the related part number 1486142080, which is likewise used in the Peugeot 806.

How do you recognize a defect in Control Unit 550539800?

A defect in Control Unit 550539800 primarily manifests as a permanently illuminated or intermittently flashing airbag warning light on the instrument cluster. Additionally, fault codes are stored in the error memory that cannot be cleared using conventional diagnostic equipment, indicating either an internal fault or retained crash data.

The illumination of the airbag warning light is the clearest indicator. It signals that the entire restraint system is disabled and would not deploy in another crash.

During a workshop diagnosis, it is found that while the control unit reports errors, these cannot be erased—typical behavior after crash data has been stored.

In which vehicles is Control Unit 550539800 installed?

The Airbag Control Unit with part number 550539800 was specifically developed for the Peugeot 806. It is found in the first generation (806 I) from 1994 to 1998, as well as in the revised facelift model of this series, produced until 2002.

At Airbag24, we specialize in repairing this control unit and offer reliable restoration for the precisely specified vehicle models.

Our repairs thus cover the following model ranges: Peugeot 806 I (1994–1998) and the Peugeot 806 I Facelift (1998–2002).

How is Control Unit 550539800 professionally repaired?

Professional repair at Airbag24 focuses on fully restoring the original factory condition. Following an initial inspection, stored crash data is deleted using specialized software. If electronic faults are present, they are addressed at the component level before a final functional test validates the repair.

Once the control unit arrives at Airbag24, it undergoes a thorough analysis to identify the exact cause of the fault—whether it’s simply data deletion or an additional hardware issue.

The core process involves resetting the crash data. This is performed using equipment that goes beyond standard automotive workshop capabilities, ensuring safe and complete erasure.

After successful repair and passing the final inspection, the control unit is prepared for return shipment. We provide 2 years' statutory liability for defects on all repairs.