105 airbag control unit fault

What does error code 105 on the airbag control unit indicate?

Error code 105, often associated with part numbers such as 0 285 001 105, indicates a critical internal fault in the airbag control unit. The cause is usually hardware-related, such as crash data stored after an accident that locks the unit, or a failure of electronic components. As a result, the system becomes inoperable.

This error code signifies that the control unit has failed its internal self-test. Following an airbag deployment, crash data is permanently recorded in the unit’s memory, triggering a deliberate safety lock to prevent reuse without professional inspection.

In addition to crash data, defects in internal components like processors or resistors can also trigger this error. The control unit can then no longer communicate correctly with the sensors and airbags, compromising vehicle safety. The English equivalent of this error is often designated as B0105.

How do you recognize error code 105?

The primary symptom of error code 105 is a continuously illuminated airbag warning light on the instrument panel. Additionally, it is often impossible to access the airbag control unit via diagnostic equipment, as communication is blocked. Reading or clearing error codes fails.

The airbag warning light does not turn off after starting the vehicle. This is a clear indication that the safety system has detected a serious fault and is not operational.

Workshops frequently find that no connection can be established with the control unit. Requests through the OBD interface remain unanswered, or error messages such as “control unit not responding” or “component defective” appear.

In some cases, the error may occur sporadically, for example during temperature fluctuations, suggesting a thermally induced failure of components on the circuit board.

What causes error code 105?

The main cause of error code 105 is crash data stored in the control unit’s memory after an accident, which locks the system. Another common cause is internal hardware failures, where electronic components on the circuit board fail. External factors such as cable breaks can mimic these symptoms.

After every airbag deployment—even minor collisions like a knee airbag activation—a permanent entry is written into the control unit’s memory. This “crash-lock” function cannot be cleared using standard diagnostic tools and requires specialized repair.

Internal components may fail due to aging, vibrations, or thermal stress, leading to an internal fault that the system detects and reports via error code 105.

It is important to rule out external sources of error before removing the control unit. Damaged cables—especially under the front seats—or a discharged vehicle battery can falsely suggest a defect in the control unit.

Which models experience error code 105?

Error code 105 and related part numbers such as 0 285 001 105 or 212388-105 primarily occur in specific models from Volvo, VW, and Peugeot. Older model series, such as the first-generation Volvo S80, are particularly affected, but vehicles like the Peugeot 107 are also commonly impacted.

At Airbag24, we repair control units exhibiting this fault pattern for a range of specific vehicles, including:

Volvo: S80 TS (model years 1998–2003) and the S80 TS facelift (model years 2003–2006).

Peugeot: 107, often equipped with part number 212388-105.

VW: Various models fitted with the Bosch control unit bearing part number 0 285 001 105.

How is error code 105 professionally repaired?

Professional repair of error code 105 involves refurbishing the removed airbag control unit. At Airbag24, upon receipt of the unit, stored crash data is erased at the chip level, and any defective electronic components are replaced. Two years' statutory liability for defects is provided on all repairs.

Before dismantling the control unit, a diagnosis at a qualified workshop is recommended to rule out external causes such as cable breaks. The diagnostic report should be included with the shipment to expedite analysis.

The repair process at Airbag24 is designed for shipping. The defective control unit is securely packaged and sent along with the repair form.

Our technicians perform a detailed electronic analysis. Subsequently, crash data is removed from the memory chip (EEPROM), and damaged components are carefully replaced. After successful repair and functional testing, the unit is returned to the customer.

An important safety note: All work on the airbag system, including the removal and installation of control units, requires certification of competence and must be performed exclusively by qualified technicians.