Airbag control unit with part number HNA9670BA

What is the function of the HNA9670BA airbag control unit?

The HNA9670BA is an original airbag control unit manufactured by Autoliv, specifically designed for classic Jaguar models such as the XJ X300 (1994–1997). As the central control unit of the occupant restraint system (SRS), it processes data from crash sensors and is responsible for deploying airbags and seatbelt pretensioners in the event of a collision. It is often used as a passenger‑side airbag control unit.

As the “brain” of the restraint system, the HNA9670BA continuously monitors all connected components—from the impact sensors at the front of the vehicle to the airbag modules and seatbelt pretensioners. Each time the vehicle is started, it performs a self‑test to ensure the entire system is functioning properly.

Its technical specifications as an original Autoliv part guarantee precise compatibility with the vehicle architecture of the Jaguar XJ X300 and the Jaguar Vanden Plas X300. In particular, vehicles with a VIN ranging from 720125 to 812255 feature this module as the passenger‑side airbag control unit, underscoring its specific role within these models’ safety systems.

Why does the HNA9670BA fail? Common defects

A failure of the HNA9670BA is most often caused by stored crash data following an accident, which locks the unit. Other causes include internal electronic faults, damage from overvoltage or moisture ingress—conditions that can lead to board‑level failures and complete loss of communication.

The most common cause of malfunction is the storage of crash data. After an airbag deployment, the control unit locks itself for safety reasons and becomes inoperable. This condition cannot be cleared using standard workshop diagnostic tools and requires specialized repair involving erasing the data on the memory chip.

Electronic faults are another frequent source of issues. Overvoltage—such as that caused by jump-starting—can damage sensitive components like processors or voltage regulators. Similarly, moisture intrusion may result in corrosion and short circuits on the circuit board. Such internal failures typically manifest as specific error codes like 65535 or 93F9, indicating irreparable internal damage that can only be resolved through component‑level repairs.

How do you recognize a defective HNA9670BA?

The clearest symptom of a defect in the HNA9670BA is a permanently illuminated or flashing SRS airbag warning light on the instrument cluster. Often, communication between the diagnostic tool and the control unit also breaks down, complicating troubleshooting and pointing directly to an internal fault within the module.

The airbag warning light serves as the vehicle’s primary alert signal. If it fails to extinguish after the engine starts, the onboard diagnostic system has detected a critical fault in the restraint system. In this state, the entire airbag system is disabled, posing a significant safety risk in the event of a crash.

Another clear indication is a complete loss of communication. When a workshop attempts to read the fault memory via the OBD interface, the airbag control unit remains unresponsive. Error codes such as 65535, 93F9, or generic CAN‑bus errors are typical entries found in other control units, signaling a failure of the airbag module.

In which vehicles is the HNA9670BA installed?

The HNA9670BA airbag control unit is a specific original part from Autoliv, primarily used in classic Jaguar sedans from the 1990s. It is mainly associated with the Jaguar XJ of the X300 series (1994–1997) and its sister model, the Jaguar Vanden Plas X300.

At Airbag24, we repair the HNA9670BA for the following specific models:

Jaguar XJ X300 (model years 1994–1997)

Jaguar Vanden Plas X300

It should be noted that in these vehicles, this module frequently serves as the passenger‑side airbag control unit, especially among cars with VINs ranging from 720125 to 812255. Precise identification via the part number is essential for successful repair.

How is the HNA9670BA professionally repaired?

At Airbag24, repairing the HNA9670BA follows a standardized process. It begins with an initial inspection to analyze the fault, followed by addressing the root cause—whether resetting crash data or replacing defective components. A final functional test ensures the unit is fully operational again. Repairs come with 2 years' statutory liability for defects.

After submitting the removed control unit to Airbag24, the repair proceeds according to a proven, systematic procedure. First, the device is connected to specialized test benches to verify the reported fault and establish an accurate diagnosis.

Subsequently, the actual repair is carried out by experienced mechatronics technicians. If stored crash data is available, it is erased and the control unit is restored to its factory settings. In cases of hardware damage—such as that caused by overvoltage or moisture—the defective components on the circuit board are identified and replaced with new, high-quality parts.

Following repair, each control unit undergoes a comprehensive final inspection to ensure the proper functioning of all systems. The unit is returned in plug-and-play condition, eliminating the need for additional vehicle coding. We provide 2 years' statutory liability for defects on every repair performed.