Airbag control unit with part number XR843849

What is the function of the airbag control unit XR843849?

The airbag control unit with part number XR843849 is the central control module of the occupant restraint system (SRS) in Jaguar S-Type models of the X200 series. It is responsible for processing signals from crash sensors and precisely deploying airbags and seatbelt pretensioners in the event of a collision.

As the “brain” of the safety system, this module continuously monitors all connected components, including the acceleration sensors at the front and sides of the vehicle, as well as the seat occupancy detection system. It analyzes incoming data in real time to assess the severity of an impact and ensure targeted activation of the safety devices.

The software and hardware of this control unit are specifically tailored to the vehicle architecture of the Jaguar S-Type X200, its facelift variants, and the S-Type R. This specialized configuration ensures that the restraint system responds optimally to the vehicle’s crash structure and dynamics.

Why does the airbag control unit XR843849 fail?

The most common cause of failure for the XR843849 control unit is the storage of crash data after an accident, which permanently locks the device. Other causes include internal electronic malfunctions leading to communication loss, as well as physical issues such as damaged wiring, loose connectors, or water damage.

Following a traffic accident—even minor collisions where the airbags did not deploy—the control unit irrevocably writes crash data into its internal memory. This safety mechanism locks the module to prevent further use of a potentially damaged system and illuminates the SRS warning light.

Hardware defects on the circuit board are another frequent cause. These include faulty electronic components or problems with connector contacts, which can result in total failure or sporadic malfunctions. In such cases, communication via a diagnostic tool is often impossible.

This control unit is also known under alternative part numbers XR845865, XR841285, XR841286, XR843850, XR845339, 4R83-14B321-AC, and XR842811, and exhibits a similar fault pattern.

How do you recognize a defect in the XR843849 control unit?

A defect in the XR843849 control unit primarily manifests as a permanently illuminated or flashing airbag warning light (SRS light) in the instrument cluster. Additional clear symptoms include readable fault codes such as “Internal Error” or “Crash Data Stored,” along with complete refusal to communicate with a diagnostic tool.

The most obvious sign for the driver is the active SRS warning light. It fails to extinguish after starting the vehicle, signaling a serious fault in the restraint system that compromises passenger safety.

In the workshop, the defect often becomes apparent when the control unit no longer responds to diagnostic requests via the OBD interface. The tester cannot establish a connection, preventing detailed fault analysis and pointing directly to an internal malfunction within the module.

If communication remains possible, specific fault codes stored in the error memory provide clear indications. Entries like “Crash Data Stored” or a general “Internal Control Unit Error” confirm that the root cause lies within the device itself, rather than external components such as sensors or wiring.

In which models is the airbag control unit XR843849 installed?

This control unit is specifically designed for the Jaguar S-Type platform of the X200 generation. It is used in pre-facelift, facelift, and high-performance R models of this series, ensuring broad coverage across this vehicle family.

At Airbag24, the XR843849 control unit is refurbished for the following specific Jaguar models:

Jaguar S-Type X200 (1999–2002)

Jaguar S-Type X200 Facelift (2002–2007)

Jaguar S-Type R X200

What are the benefits of repairing the XR843849?

The key advantage of repair is substantial cost savings—up to 70% compared to purchasing a new unit, which can cost as much as €934. Additionally, there is no need for time-consuming re-coding, as the vehicle-specific configuration is preserved, and the repair comes with 2 years’ statutory liability for defects.

Repair represents the most economical solution. Rather than investing in an expensive new component, the existing defective unit is professionally restored. This not only protects your budget but also offers a sustainable alternative to replacement.

Since the original control unit is repaired, its factory coding and programming remain fully intact. After reinstallation, the device is immediately ready for use (plug-and-play), eliminating the need for costly and time-consuming reprogramming at a specialist workshop.

Two years' statutory liability for defects is provided on every repair performed. This ensures you receive a reliable, long-lasting solution that matches the quality of a new part.

How is the XR843849 control unit professionally repaired?

At Airbag24, repairs follow a standardized process. Following an initial analysis—during which the fault memory is read—the electronic restoration takes place. This includes erasing crash data at the chip level, replacing defective components, and conducting a final functional test to ensure quality.

Upon receipt at Airbag24, the control unit undergoes a thorough diagnosis. Here, the error codes submitted by the customer are verified, and the hardware is inspected for visible damage.

The core of the repair involves eliminating the root cause of the fault. Specialized technicians either erase the stored crash data directly from the memory chip or replace faulty electronic components on the circuit board. This intervention restores the module’s full functionality.

Subsequently, the refurbished control unit undergoes a comprehensive functional test on a test bench that simulates real‑world driving conditions. Only after successful completion is the unit approved for return shipment, backed by 2 years’ statutory liability for defects.