Airbag control unit with part number 550790300

What is the function of Airbag Control Unit 550790300?

The airbag control unit with part number 550790300 is the central control module for the occupant safety system (SRS) in the Renault Avantime I. It continuously monitors all relevant sensors, processes their data, and ensures the precise deployment of airbags and seatbelt pretensioners in the event of a crash.

As an original OEM module (Original Equipment Manufacturer), it serves as the brain of the entire restraint system. It is also known under alternative manufacturer numbers from Autoliv: 6025410166 or 6025409466. The primary task of this unit is to process signals from acceleration and crash sensors distributed throughout the vehicle.

Under normal operating conditions, the control unit performs continuous self-tests and monitors the functionality of all connected components, such as airbag initiators, seatbelt pretensioners, and sensors. In case of a malfunction, the airbag warning light illuminates to alert the driver.

Why does control unit 550790300 fail?

The most common cause of failure for control unit 550790300 is the storage of crash data after an accident, which causes the unit to become internally locked. Other typical defects include complete communication failures with the diagnostic tester or internal hardware malfunctions, often indicated by error codes such as B1239.

Even if the airbags did not deploy during a collision, the unit permanently stores crash-event data. This internal lock renders the control unit unusable for safety reasons and requires specialized repair to reset it.

Another frequent issue is total loss of communication. The control unit no longer responds to requests from diagnostic tools (OBD2), making fault diagnosis impossible. The root cause is often defective electronic components on the circuit board, such as capacitors or processors.

Internal faults, frequently signaled by error code B1239 ("Airbag Diagnostic Sensor Unit malfunctioning"), also point to hardware damage. Less commonly, moisture ingress or improper repair attempts can lead to complete failure.

How do you recognize a defect in control unit 550790300?

A defect in control unit 550790300 primarily manifests as a constantly illuminated or faintly glowing airbag warning light in the instrument cluster. Additionally, it often becomes impossible to access the control unit via a diagnostic tool or read out error codes, indicating total failure.

The most obvious symptom is the persistently lit SRS warning light. It does not extinguish after starting the vehicle, signaling that the entire airbag system is disabled and will not function in the event of a crash.

A clear technical indicator is the lack of communication. When a professional workshop attempts to read the control unit using a diagnostic device, no connection is established—the unit is no longer responsive within the vehicle’s electrical network.

In rare cases, unusual electrical phenomena may also occur. A specific symptom unique to this control unit is an activated speedometer illumination that lights up when the vehicle is locked. This suggests an internal short circuit or faulty power supply within the device.

In which vehicles is control unit 550790300 installed?

The airbag control unit with part number 550790300 is primarily intended for the Renault Avantime I model years 2001–2003. Although specifically developed for this model, compatibility with other Renault models, such as the Vel Satis, may exist in isolated cases.

At Airbag24, we repair control units with part number 550790300, as well as the associated Autoliv numbers 6025410166 and 6025409466, for the following specific model:

Renault: Avantime I (model years 2001–2003)

Repair services are highly specialized and performed by experienced technicians.

How does the repair of 550790300 proceed at Airbag24?

The repair of control unit 550790300 at Airbag24 includes a professional diagnosis, deletion of stored crash data (crash reset), and replacement of defective electronic components on the circuit board. Upon successful restoration, full functionality of the unit is ensured, and you receive 2 years’ statutory liability for defects.

The process begins after the control unit has been carefully removed from the vehicle. Please send us the unopened component along with the completed repair order. It is crucial that no independent repair attempts have been made, as this could compromise the chances of success.

Upon receipt at Airbag24, our technicians perform a comprehensive analysis to identify the exact cause of the fault. The repair is then carried out, typically involving resetting the crash data and replacing defective components with genuine parts. Finally, the control unit undergoes a functional test to ensure proper operation.