00654-001 airbag control unit fault

What does error code 00654-001 mean?

Error code 00654-001 indicates a specific fault in the driver-side seatbelt pretensioner circuit. The cause is an implausible resistance measurement detected by the airbag control unit. This suggests faulty wiring, a defective pretensioner mechanism, or an internal fault within the control unit itself.

Technically, the airbag control unit continuously monitors the electrical resistances of all safety‑related components. The driver’s seatbelt pretensioner is connected via its own dedicated circuit. If the measured resistance deviates from the target value stored in the control unit, this is interpreted as a fault and error code 00654-001 is logged in the fault memory.

This deviation can be caused by excessively high resistance (e.g., due to a broken wire or corroded contacts) or excessively low resistance (e.g., due to a short circuit). In such cases, the system can no longer guarantee proper operation of the seatbelt pretensioner and, for safety reasons, deactivates parts of the occupant protection system.

How do you recognize error code 00654-001?

The primary and unmistakable symptom of error code 00654-001 is the persistent illumination of the airbag warning light (also known as the SRS lamp) on the instrument cluster. This indicates that the occupant protection system is not fully functional and that the airbags may be deactivated in the event of a crash.

The warning light typically fails to extinguish after starting the vehicle or begins to stay lit permanently after a short period. Occasional flashing is also possible but likewise points to a serious system fault requiring immediate diagnosis.

In addition to the active warning light, the fault is recorded in the airbag control unit’s fault memory and can be read out using an appropriate diagnostic tool. Other external symptoms usually do not appear; the real danger lies in the potential loss of protective functionality during an accident.

What causes error code 00654-001?

The main cause of error code 00654-001 is a physical issue in the driver-side seatbelt pretensioner circuit. This includes defective pretensioners with abnormal internal resistance values, cable breaks in the supply line, corroded connectors, or, more rarely, an internal defect within the control unit itself.

A very common source of failure is the connectors and cables beneath the driver’s seat. Due to the constant movement of the seat when adjusting it, cable breaks or loose connections can develop over time, leading to the measured resistance deviations.

The seatbelt pretensioner itself or the seatbelt mechanism may also suffer internal wear or exhibit defects. In rarer cases, the fault originates on the airbag control unit’s circuit board, where the input circuitry for resistance measurement is damaged.

Related error codes and diagnostics for the airbag system

In addition to the specific code 00654-001, there are other general error codes indicating faults within the airbag system. Code 65535, often seen in VW and Audi vehicles, signals an irreparable internal control unit defect. At BMW, error 93F9 frequently points to damage caused by overvoltage.

Mercedes-Benz models often display error B1000, which indicates a complete loss of communication with the control unit, or specific CAN errors signaling issues in the data bus. These faults generally suggest more severe, internal hardware defects within the control unit.

Diagnostics always begin with a visual inspection of accessible components such as connectors. Subsequently, the fault memory is read using a diagnostic system. Based on the error code, the root cause can be precisely narrowed down—whether it’s a faulty sensor, a damaged cable, or an internal defect in the control unit.

Which vehicles are affected by error code 00654-001?

Error code 00654-001 primarily occurs in certain Bentley models. Vehicles from the luxury segment produced in the 1990s and 2000s, which utilized this particular system architecture, are especially affected. For these exclusive models, repair is often the most cost-effective solution.

At Airbag24, we repair airbag control units displaying error code 00654-001 for the following Bentley models:

Bentley Azure Generation 1 (2006–2011), Bentley Continental T Generation 1 (1991–2002), and Bentley Continental Supersports Mk1.

How is error code 00654-001 professionally repaired?

Professional repair requires component-level analysis. After removal, the control unit is examined in the lab to pinpoint the exact cause of the resistance deviation. Defective components on the circuit board are then replaced, and all relevant solder joints are reworked to restore proper function of the measurement circuits.

After submitting the removed control unit to Airbag24, a systematic repair process follows. First, the fault memory is read out and an initial hardware inspection is performed. The technicians focus on the input circuits responsible for monitoring the seatbelt pretensioner circuit.

Defective components are replaced with new, specification-compliant parts. If crash data was additionally stored after an accident, it is also completely and irreversibly erased from the control unit’s memory during the repair process.

Upon completion of the refurbishment, each control unit undergoes a comprehensive functional test on a dedicated test bench. This ensures that the device operates flawlessly again and accurately measures all resistance values. We provide 2 years' statutory liability for defects on the completed repair.