Airbag control unit with part number XR845339

What is the function of the airbag control unit XR845339?

The airbag control unit with part number XR845339 is the central control module for the occupant protection system in certain Jaguar S-Type models. It continuously monitors all connected sensors and components, evaluates data in the event of a collision, and determines whether to deploy the airbags and seatbelt pretensioners.

As the brain of the passive safety system, this module processes signals from acceleration and pressure sensors distributed throughout the vehicle. It detects the type and severity of an impact and selectively activates the necessary restraint systems to provide optimal occupant protection.

A key function is also storing system fault codes and, in the event of a crash, permanently recording crash data. These records lock the control unit after an incident, preventing reuse without professional inspection and repair.

Why does the XR845339 control unit fail? Typical defects

The most common cause of failure for the XR845339 control unit is the storage of crash data following an accident. Other defects arise from aging electronic components, moisture ingress, or internal faults in sensors and circuit traces. Related part numbers such as XR845865 exhibit similar failure patterns.

After an accident—even a minor one like rear-end damage without airbag deployment—a crash record is stored in the control unit’s internal memory. This entry is permanent and disables the entire airbag system, making repair or replacement unavoidable.

Hardware failures are another widespread cause. These include individual electronic component breakdowns due to aging, fine cracks in circuit traces caused by vibrations, or corrosion from penetrating moisture. Faults in internal sensors or components with tight tolerances can also lead to complete system failure.

The aforementioned defects are not limited to part number XR845339; they also occur in technically related variants such as XR841285, XR841286, XR843849, XR843850, 4R83-14B321-AC, and XR842811, which may be installed in the same vehicle models.

How do you recognize a defect in the XR845339 control unit?

The clearest symptom of a faulty XR845339 airbag control unit is the permanently illuminated airbag warning light on the instrument cluster. Often, it is also impossible to access the control unit with a diagnostic tool or clear stored fault codes.

An active airbag warning light indicates a malfunction in the restraint system, meaning the airbags will not deploy—or will not deploy correctly—in the event of a crash. Customers frequently report a “Airbag error during startup” message that remains displayed.

Another clear sign is loss of communication. If the workshop cannot establish a connection between its diagnostic device and the airbag control unit, this points to a severe internal fault within the module.

If diagnostics are still possible, specific, non‑erasable fault codes may be present. Real-world examples include error messages related to the driver’s airbag or side sensors that persist even after replacing external components.

In which vehicles is the XR845339 control unit installed?

The airbag control unit with part number XR845339 is specifically designed for the Jaguar S-Type X200 series. It is used in both the original models, the facelift version, and the sporty R variant.

At Airbag24, we repair the XR845339 control unit and equivalent variants for the following models:

Jaguar S-Type (X200) model years 1999–2002

Jaguar S-Type (X200 Facelift) model years 2002–2007

Jaguar S-Type R (X200)

Is repairing the XR845339 control unit worthwhile?

Yes, repairing the XR845339 control unit is an economically and technically sensible solution. It saves 30–50% compared to purchasing a new unit. A major advantage is that no re‑coding or programming is required after repair.

A new control unit often costs over €200 and must additionally be coded to the vehicle at the workshop. Repairing the original part is significantly cheaper and restores full functionality without altering the vehicle’s configuration.

Since the repaired unit retains its original coding, it works immediately upon reinstallation (plug-and-play). This saves valuable time and reduces additional workshop expenses. We also offer 2 years’ statutory liability for defects on every repair performed.

How does the repair process work at Airbag24?

The repair process begins with the professional removal of the control unit from the vehicle. After sending it to Airbag24, a detailed diagnosis is performed. Defects are then resolved by clearing crash data, replacing faulty components, and verifying the software, before the unit is tested and returned to you.

Before removal, we recommend reading out the vehicle’s fault memory and attaching the shipping log. The control unit should be carefully packaged and shipped with insurance to prevent transport damage.

Upon receipt at Airbag24, technicians conduct a thorough inspection to identify the exact cause of the fault. Depending on the findings, repairs may involve resetting stored crash data, repairing circuit traces, or replacing defective electronic components. In some cases, a software reset may also be required.

Following successful repair, the control unit undergoes a final test to ensure flawless functionality across all systems. Of course, you receive 2 years' statutory liability for defects on the repair.