B1108 airbag control unit fault

What does error code B1108 in the airbag control unit indicate?

Error code B1108 points to a problem directly within the airbag control unit, detected by the device’s internal self-diagnosis. Often, an internal component failure—such as the diagnostic sensor—is the cause. This causes the control unit to switch into a safety mode, no longer ensuring proper operation of the airbag system.

Technically, the airbag control unit performs a comprehensive self-test every time the vehicle is started. If irregularities or defects are detected in internal components like processors, memory modules, or sensors, error code B1108 is stored in the fault memory.

This error code indicates that the integrity of the control unit hardware may be compromised. The system can no longer reliably determine whether and when the airbags or seatbelt pretensioners should deploy, so it is placed in a passive state for safety reasons.

How do you recognize error code B1108?

The most obvious symptom of error code B1108 is the permanently illuminated airbag warning light on the instrument cluster. This light does not turn off after starting the engine, indicating an active, safety‑relevant fault in the restraint system. As a result, the airbags and seatbelt pretensioners are usually deactivated.

In addition to the warning light, some vehicles may display corresponding error messages on the onboard computer’s screen, signaling a malfunction in the airbag system.

During a diagnosis at a workshop, error code B1108 can be read from the airbag control unit’s fault memory. In some cases, communication with the control unit may be completely disrupted, complicating diagnosis and providing further evidence of a serious internal defect.

What causes error code B1108?

The main causes of B1108 are varied, ranging from internal electronic faults to external influences. Common issues include poor electrical connections—such as loose airbag connectors caused by seat movement—faulty cables, water damage, or short circuits directly within the control unit. After accidents, stored crash data is also a typical culprit.

At the hardware level of the control unit, defective components like transistors, chip parts, fuses, or damaged solder joints can trigger the error. In particular, the diagnostic sensor integrated into the control unit may be affected by a defect.

External factors such as moisture leading to corrosion on the circuit board or severe vibrations can also damage the sensitive electronics and result in the storage of error code B1108.

Another frequent cause is the retention of crash data following an accident. In this case, the control unit locks itself and reports an internal fault that can only be resolved through professional repair and reset.

In which vehicles does error code B1108 occur?

Error code B1108 is particularly well known for specific models. At Airbag24, we offer expert repairs for airbag control units in vehicles such as the Bentley Eight Mk1 and the Toyota Supra A90 (from model year 2019 onward), which are frequently affected by this issue.

At Airbag24, we have already successfully repaired this error code in control units of the following models:

Bentley: Eight Mk1

Toyota: Supra A90 (2019–present)

How is error code B1108 professionally repaired?

Professional repair of error code B1108 at Airbag24 involves precise electronic analysis at the component level. Defective components such as transistors or chips are replaced using high‑precision soldering techniques. The control unit is then subjected to a full functional test to ensure correct operation.

After submitting the removed control unit, it is first scanned with specialized diagnostic software to confirm error code B1108 and any additional faults. This is followed by a visual inspection of the circuit board for obvious damage, such as corrosion or faulty solder joints.

Next comes component‑level repair. Technicians inspect and replace defective electronic parts. If crash data was stored after an accident, it is completely and safely erased during the repair process.

Following restoration, the control unit is tested in a controlled environment to verify that all functions have been fully restored and that the airbag warning light correctly extinguishes in the vehicle. We provide 2 years' statutory liability for defects on every repair.

Is repairing the control unit worthwhile?

Yes, repairing the airbag control unit is the most cost‑effective solution. It offers significant savings compared to purchasing an expensive new part. Moreover, restoring the original component eliminates the need for time‑consuming coding or reprogramming after installation.

A new airbag control unit from the manufacturer often comes with high costs. Repair offers a significantly more affordable alternative, without compromising safety or functionality.

Since the vehicle-specific original control unit is repaired, all coding and configurations are preserved. After repair, the unit can be easily reinstalled (plug-and-play) and is ready for immediate use, saving you additional workshop costs and time.