Airbag control unit with part number FH22 14D374 AC

What is the Airbag Control Unit FH22 14D374 AC?

The airbag control unit with part number FH22 14D374 AC is the central control module for the Supplemental Restraint System (SRS) in the Land Rover Discovery 4. It processes data from crash sensors, controls the deployment of airbags and seatbelt pretensioners during a collision, and stores relevant crash data in its internal memory.

This specific SRS module was developed for the Land Rover Discovery 4 (L319) model years 2009 to 2013, as well as the facelifted version through 2017. As the “brain” of the passive safety system, it ensures that all components—airbags, seatbelt systems, and sensors—work together in a coordinated manner in the event of an accident.

After deployment, the unit permanently stores the crash data. This storage causes the airbag warning light in the cockpit to remain illuminated, and the system becomes locked against further deployment until the data is professionally erased.

Why Does the FH22 14D374 AC Control Unit Fail?

The most common cause of failure for the FH22 14D374 AC control unit is the retention of crash data after an accident, which results in the module being locked. Other defects arise from electrical disturbances such as a dead battery, jump-start attempts, or internal component failures that can occur even without a crash.

The primary reason for failure is the immobilization of the control unit following airbag deployment. The module stores so‑called “hard codes” in its EEPROM, which cannot be cleared using standard diagnostic equipment. Although the airbags and seatbelt pretensioners must be replaced, the control unit itself can often be restored through reprogramming.

Electrical malfunctions are another frequent source of issues. Voltage spikes caused by jump-starts, a deeply discharged battery, or loose connectors and damaged wiring harnesses can lead to internal faults. Such defects often manifest as error codes like “ECU fault” or communication problems, even when no crash has occurred.

In some cases, the root cause lies not in the control unit itself but in peripheral components. Faulty crash sensors or broken cables can also trigger error codes in the SRS module. Therefore, precise diagnostics are essential to accurately pinpoint the source of the problem, since simple “soft codes” can often be reset with a scan tool.

How Do You Recognize a Fault in the FH22 14D374 AC?

A defective FH22 14D374 AC airbag control unit almost always shows up as a persistently illuminated airbag warning light (SRS indicator) on the instrument cluster. Additionally, OBD diagnostics can reveal specific error codes such as “Crash Data Stored” or “ECU Fault,” and in some cases, communication with the control unit may become impossible.

The clearest sign is the active airbag warning light. It does not turn off after starting the engine, indicating that the entire restraint system is disabled and would fail to deploy in a future crash.

During diagnosis with a workshop tester, specific error codes are frequently read out. Codes pointing to stored crash data or an internal control unit malfunction directly indicate a defect in the SRS module. These errors typically cannot be cleared without specialized repair procedures.

Another symptom may be complete loss of communication. If the workshop attempts to access the control unit via the OBD interface, the connection fails, suggesting a more serious internal electronic fault.

In Which Vehicles Is the FH22 14D374 AC Control Unit Installed?

The airbag control unit with part number FH22 14D374 AC is specifically used in vehicles manufactured by Land Rover. It is primarily designed for the Land Rover Discovery 4, covering model years from 2009 through the end of the series in 2017.

At Airbag24, we repair the FH22 14D374 AC control unit for the following vehicle lineup. Compatibility is guaranteed for these specific models.

Land Rover: Discovery 4 (L319), model years 2009–2013, as well as the facelifted version from 2013–2017. It is commonly found in diesel‑powered variants, such as the V6 TD SE.

How Is the FH22 14D374 AC Control Unit Professionally Repaired?

Professional repair of the FH22 14D374 AC control unit at Airbag24 involves reading out and erasing the stored crash data through EEPROM reprogramming. Upon receipt, the module is thoroughly analyzed, the original firmware is restored, and the device is tested for full functionality, backed by 2 years’ statutory liability for defects.

The process ideally begins with a vehicle diagnosis to rule out external sources of failure. For repair, the control unit must be removed, typically located beneath the center console, dashboard, or one of the seats. Importantly, before removal, disconnect the battery for at least five minutes.

After sending your unit to Airbag24, our technicians perform a thorough analysis. The core of the repair is reprogramming the internal memory (EEPROM), which overwrites the hard codes and crash data, restoring the module to its factory settings and making it function like new.

Following successful programming, the control unit undergoes a final inspection. Once reinstalled in the vehicle, the airbag warning light will extinguish, and the SRS system will be fully operational again. However, if the module has suffered irreparable damage—such as from a severe accident—a replacement is unavoidable.