Airbag control unit with part number 337644-101

What is the function of the airbag control unit 337644-101?

The TRW airbag control unit 337644-101 is the central control module for the occupant restraint system (SRS) in models such as the Peugeot 108 and Citroën C1. It processes signals from the acceleration sensors to precisely deploy the airbags and seatbelt pretensioners in the event of a crash, while also storing relevant crash data in its internal memory.

This control unit, also known as the SRS ECU (Supplemental Restraint System Electronic Control Unit), is essential for vehicle passive safety. It continuously monitors all connected components—such as sensors, airbag modules, and seatbelt pretensioners—for proper functionality.

In the event of a collision, the electronics determine within milliseconds whether deployment is necessary and how intense it should be. After an accident, crash data is permanently stored in the unit’s memory, which serves a critical purpose for accident analysis—but often results in the system becoming locked.

Why does the control unit 337644-101 fail?

The most common cause of failure for the control unit 337644-101 is the storage of crash data after an accident, which locks the system. Other causes include internal electronic defects in components such as processors or capacitors, communication errors, and external factors like water damage or wiring issues.

The primary defect requiring repair is the irreversible storage of crash information. Once the control unit registers a crash and deploys the restraint systems, it self‑locks to prevent reuse without inspection. The airbag warning light remains constantly illuminated.

In addition, purely electronic malfunctions can occur. Internal processor faults, defective capacitors, or damaged memory chips can lead to total failure or malfunction. Such defects are often due to age or vibration.

The peripheral components can also play a role. Issues such as broken wires, corroded connectors, or a faulty steering wheel coil spring may trigger errors in the control unit or disrupt communication. In rare cases, water damage or mechanical damage to the housing is the root cause.

This control unit is also known under alternative OEM part numbers 89170-0H040, 89170-0H190, 89170-0H130, 89170-0H210, and B0 008 661 80, with identical fault patterns across these variants.

How do you recognize a defect in the control unit 337644-101?

A defect in the control unit 337644-101 primarily manifests as a permanently lit or flashing SRS airbag warning light on the instrument cluster. Additionally, the fault memory often contains non‑erasable entries such as “control unit defective” (error code B1000) or specific errors related to ignition circuits (e.g., B1801).

The clearest indication is the activated airbag warning light, signaling to the driver that the occupant restraint system is either non‑functional or only partially operational—and therefore would not deploy correctly in the event of a crash.

During workshop diagnostics, the problem is frequently revealed through specific error codes. Code B1000 often points to an internal fault or stored crash data, while code B1801 indicates an issue in the driver’s airbag ignition circuit—often originating in the steering wheel coil spring but sometimes caused by the control unit itself.

Another symptom may be a complete loss of communication: the diagnostic tool cannot establish a connection with the airbag control unit, complicating troubleshooting and strongly suggesting a severe internal defect.

In which vehicles is the control unit 337644-101 installed?

The TRW airbag control unit 337644-101 is mainly used in small cars from the former PSA Group and its partner brands, including the Peugeot 108, the Citroën C1, and platform‑related models. At Airbag24, this control unit is professionally refurbished for the aforementioned models.

At Airbag24, we repair part number 337644-101 and its compatible variants for the following vehicles:

Peugeot 108 I (model years 2014–2022)

Citroën C1 II (model years 2014–2022) and the C1 III (from 2014 onward)

Toyota Aygo AB40, which shares a technical platform with PSA models. Here, you’ll also find related OEM numbers such as 89170-0H020 or the designation 337644-101-95160.

How is the repair of the control unit 337644-101 carried out?

The repair of the control unit 337644-101 takes place at the component level after submission to Airbag24. First, an initial inspection is performed to accurately diagnose the fault. Depending on the nature of the defect, crash data is erased, faulty components such as processors or memory chips are replaced, and the device is reprogrammed.

Before removing the control unit, the vehicle’s fault memory should be read out. This ensures that the root cause of the fault lies in the control unit itself and not in peripheral components such as wiring or sensors.

After being sent to Airbag24, the device undergoes a standardized repair process. Using specialized diagnostic and test environments, the exact fault is pinpointed—whether it involves stored crash data or a hardware defect.

The actual repair includes erasing the crash data with proprietary software to restore the unit to its factory settings. For electronic faults, defective components on the circuit board are identified and professionally replaced.

Finally, a comprehensive functional test is performed, verifying all functions—including communication and simulated activation of the airbag circuits—in accordance with the manufacturer’s specifications. You receive 2 years' statutory liability for defects on the completed repair.