Airbag control unit with part number 590339500

What is the function of Airbag Control Unit 590339500?

The airbag control unit with part number 590339500 is the central control module for the restraint system in the Citroën ZX I. It continuously monitors signals from the crash sensors and is responsible for precisely and rapidly deploying the airbags and seatbelt pretensioners in the event of a collision. It also stores relevant system data and fault codes.

As the brain of the passive safety system, this unit constantly processes data to distinguish between normal driving conditions and an actual impact. In an emergency, it sends the critical ignition pulses to the corresponding airbag modules and seatbelt pretensioners to provide optimal protection for occupants.

In addition, the control unit performs a self-test every time the vehicle is started and communicates with all connected components of the safety system. Detected faults are stored in its internal memory and indicated by the illumination of the SRS/Airbag warning light.

Why does Airbag Control Unit 590339500 fail?

The most common causes of failure for control unit 590339500 are electronic hardware defects. These include damage caused by overvoltage or water ingress, age-related cold solder joints, and defective SMD components. Another frequent cause is the storage of crash data after an accident, which can lock the unit and require repair to restore functionality.

Voltage fluctuations in the vehicle’s electrical system—such as those caused by a weak battery or jump-starting—can damage sensitive components like voltage regulators or the microcontroller on the circuit board. Similarly, moisture entering the housing leads to corrosion and short circuits on the circuit traces.

A further key reason for apparent malfunctions is the retention of crash data. After an accident, the control unit locks itself for safety reasons—a deliberate state that nonetheless requires professional reset procedures to restore full operation.

Mechanical stress and aging can also result in hairline cracks in solder joints, leading to sporadic failures or complete loss of function. In some systems, this control unit is also known by the alternative part number 9619513280.

How do you recognize a defect in Control Unit 590339500?

A defective Control Unit 590339500 primarily manifests as the permanently illuminated airbag or SRS warning light on the instrument cluster. Often, no connection can be established with the control unit using a diagnostic tool, complicating troubleshooting. Stored fault codes such as B1000 (“control unit defective”) or blockage due to crash data are also clear indicators.

The most obvious symptom is the persistently lit airbag warning light. It does not extinguish after starting the vehicle, signaling a critical fault in the restraint system that compromises safety.

Another common sign is the lack of communication. When a workshop attempts to read the fault memory, the control unit fails to respond to the diagnostic device’s queries, indicating a severe internal malfunction.

Additionally, specific fault codes may be stored in the fault memory, directly pointing to the control unit itself. Typical codes here include B1000 or B1111, which depending on the diagnostic tool, are interpreted as “internal control unit failure” or “control unit error.”

Following an accident, the system should generally be considered compromised—even if no visible damage is present. The stored crash data blocks the control unit’s functionality, which is likewise signaled by the warning light.

In which vehicles is Control Unit 590339500 installed?

The airbag control unit with part number 590339500 is specifically designed for Citroën models. At Airbag24, we specialize in repairing this control unit for first-generation Citroën ZX vehicles, including both the original model and the facelift variant. Precise matching ensures compatibility and proper function within the vehicle.

At Airbag24, we repair part number 590339500, which is used in the following Citroën models:

Citroën ZX I (model years 1991–1994)

Citroën ZX I Facelift (model years 1994–1998)

How is Control Unit 590339500 repaired?

At Airbag24, each Control Unit 590339500 undergoes a standardized repair process. Following a comprehensive initial diagnosis to identify the fault, defective electronic components on the circuit board are replaced. Subsequently, stored crash data is professionally erased, and the unit is reset. A final functional test on a test bench confirms full operability before re‑shipping.

Upon receipt at Airbag24, a thorough visual inspection is performed to identify external damage such as corrosion or damaged connectors. The control unit is then connected to specialized test benches to verify communication and precisely read out internal fault codes.

The actual repair is carried out at the component level. Our technicians replace defective parts like voltage regulators or SMD components and professionally restore damaged circuit traces. This approach offers a sustainable and cost-effective alternative to expensive new purchases.

A crucial step is the secure and traceable erasure of stored crash data. This removes the accident‑induced immobilization of the control unit and restores full functionality. Depending on the vehicle, re‑coding or adjustments may also be necessary to ensure proper communication with the vehicle.

Finally, each repaired control unit undergoes a comprehensive final inspection. All functions are simulated under realistic conditions to confirm correct communication and deployment characteristics in an emergency. A 12‑month warranty is provided for the completed repair.

What shipping options are available?

You can either send your control unit to Airbag24 yourself at no charge or arrange a convenient UPS pickup. For the return shipment, several options are available: free standard UPS shipping, faster UPS Express shipping, and both methods also offered with cash on delivery. Personal collection on site is likewise possible.

You can securely package your defective control unit and send it directly to Airbag24 or drop it off in person. Alternatively, we offer the option to book a convenient UPS pickup from your preferred location, making the process as hassle‑free as possible.

For the return shipment after successful repair, standard UPS shipping is free of charge. If speed is essential, UPS Express shipping is available. Both shipping methods can be combined with cash on delivery if desired. Of course, you can also choose to pick up your repaired unit in person at our facility.