Airbag control unit with part number 603602400

What is the function of Airbag Control Unit 603602400?

The airbag control unit with part number 603602400 is the central control module for the occupant protection system (SRS) in the Citroën Berlingo Multispace II. It processes signals from crash sensors, deploys airbags and seatbelt pretensioners in the event of a collision, and stores relevant crash data to lock out the system.

As an SRS ECU (Supplemental Restraint System Electronic Control Unit), this component is essential for vehicle passive safety. It continuously monitors all connected sensors and components, such as airbags and seatbelt pretensioners, to ensure their proper functionality.

In the event of a collision, the control unit 603602400 determines within milliseconds which restraint systems need to be activated. After the accident, it permanently stores the crash data in its internal memory. This storage often triggers the activation of the SRS warning light and prevents further use without professional reset.

Why does control unit 603602400 fail?

The most common cause of failure for control unit 603602400 is the retention of crash data after an accident. This results in permanent system lockout and error code B1111 ("control unit defective"). Internal electronic faults, indicated by codes such as 65 3 550, are also typical causes.

Following a crash, the sensors send a signal to the control unit, which then activates the restraint systems and records the collision data in its memory. This data storage is a safety feature designed to prevent continued use of a potentially damaged system. Standard diagnostic tools at workshops usually cannot clear this lockout.

In addition to stored crash data, hardware defects on the circuit board may occur. Faulty memory chips or other electronic components can lead to internal malfunctions and complete device failure. In such cases, workshops often recommend replacing the unit at a cost of around €400, even though targeted repairs are possible.

How do you recognize a defect in control unit 603602400?

A defect in control unit 603602400 primarily manifests as the SRS airbag warning light remaining constantly illuminated in the Citroën Berlingo’s instrument cluster. Additional signs include error messages on the display or the inability to clear fault codes like B1111 using standard diagnostic equipment.

The most obvious symptom is the airbag indicator light that fails to turn off after starting the engine. This indicates a critical fault in the restraint system, compromising passenger safety.

During workshop diagnostics, specific fault codes are often read. Code B1111 ("control unit defective") directly points to an internal malfunction or stored crash data. The internal fault code 65 3 550 may also suggest a problem with this control unit.

In which vehicles is control unit 603602400 installed?

The airbag control unit with part number 603602400 is specific to various model years and trims of the Citroën Berlingo Multispace II (B9). It is used in vehicles from 2008 to 2018, including facelifted models.

At Airbag24, we repair part number 603602400 for the following Citroën models: Berlingo Multispace II B9 (model years 2008–2012), the first facelift (2012–2015), and the second facelift (2015–2018).

How is control unit 603602400 professionally repaired?

Professional repair at Airbag24 includes diagnosing the fault, addressing the root cause—such as clearing crash data or replacing defective components—and performing a final functional test. After submission, the unit is restored and returned with 2 years’ statutory liability for defects.

The process begins with the careful removal of the control unit, typically located in the center console beneath the handbrake lever. Precise positioning should be verified against the vehicle’s repair manual.

Upon receipt at Airbag24, technicians conduct a thorough analysis. The most common procedure is resetting the stored crash data, returning the control unit to factory settings. For internal faults, defective electronic components on the circuit board are identified and replaced.

Once successfully repaired, the control unit regains full functionality. After reinstalling it in the vehicle, it may still be necessary to clear any remaining fault codes in the vehicle’s diagnostic system using appropriate equipment. You receive 2 years' statutory liability for defects on the repair.

Is repairing control unit 603602400 worthwhile?

Yes, repair represents an economically and technically sensible alternative to costly new purchases. You can save 30–50% compared to buying a new unit, which often costs over €400. Repair offers a sustainable solution backed by expert specialists and 2 years’ statutory liability for defects.

The biggest advantage lies in the substantial cost savings. While a new control unit costs around €400, a professional repair is significantly more affordable and restores the original part’s full functionality.

By refurbishing your existing control unit, you also help avoid generating electronic waste, making this repair an environmentally friendly choice. You can rely on a proven process carried out by experienced technicians, backed by 2 years’ statutory liability for defects for added peace of mind.