Airbag control unit with part number 65 77 9 258 350

What is the function of Airbag Control Unit 65 77 9 258 350?

The airbag control unit with part number 65 77 9 258 350 is the central safety component in the BMW 1 Series F21. It processes signals from crash sensors in real time and determines whether to deploy airbags and seatbelt pretensioners, providing optimal protection for occupants in the event of a collision.

As the brain of the passive safety system, this control unit monitors all connected components. It continuously checks the functionality of sensors, ignition circuits, and airbag modules. Upon detecting a fault or after an accident, the system is deactivated for safety reasons, and the airbag warning light on the instrument cluster illuminates.

The proper functioning of this unit is therefore critical to the overall vehicle’s safety. A failure will inevitably result in no airbags deploying during a real‑world crash.

Why does control unit 65 77 9 258 350 fail?

The most common cause of failure for control unit 65 77 9 258 350 is the storage of crash data following an accident. Other defects are often hardware‑related, such as internal faults in the step-up converter, water damage, corrosion, or aging of electronic components, leading to communication issues.

After a crash, crash data is permanently stored in the control unit’s internal memory. This lockout mechanism ensures safety by preventing further use without professional inspection and repair. The unit then reports itself as defective and must be reset.

Frequent internal hardware failures manifest through specific diagnostic trouble codes. For example, BMW models commonly display errors such as 0093DB (SIM: control unit in undefined state), 0X93DB (step-up converter faulty), or 930ABD/ACSM, indicating an internal control module error. These faults typically stem from defective circuit board components or poor solder joints.

External factors like moisture ingress can also lead to corrosion at connectors and on the circuit board, damaging electronic circuits and causing total failure.

How do you recognize a defect in control unit 65 77 9 258 350?

The primary and clearest symptom of a defect in control unit 65 77 9 258 350 is the persistently illuminated airbag warning light on the dashboard. This indicates a complete failure of the restraint system, with all airbags and seatbelt pretensioners deactivated for safety reasons.

The red warning light does not extinguish after starting the vehicle. This is a clear sign that the control unit has detected a critical fault—whether due to stored crash data or an internal hardware issue.

In many cases, communication with the control unit via a diagnostic tool is also impossible. The workshop cannot read the fault memory because the module no longer responds to requests over the OBD interface, complicating diagnosis and pointing to a severe internal malfunction.

In which vehicles is control unit 65 77 9 258 350 installed?

Part number 65 77 9 258 350 is specifically designed for BMW models. It is primarily used in the BMW 1 Series F21. At Airbag24, we offer professional repair services for this control unit, which is installed in the following vehicles.

At Airbag24, we repair part number 65 77 9 258 350 for these models:

BMW 1 Series F21 3‑door (model years 2012–2019)

How is control unit 65 77 9 258 350 professionally repaired?

At Airbag24, repairing the control unit follows a multi‑stage process. First, the fault memory is read to identify the exact cause. Next, crash data is erased, defective hardware components are replaced, and the software is restored, followed by a final functional test.

Upon receipt at Airbag24, the control unit undergoes a thorough initial inspection. Technicians analyze stored diagnostic codes to distinguish between software issues, retained crash data, or tangible hardware defects.

The core of the repair often involves erasing crash data using specialized hardware and software tools, restoring the unit to its factory condition. For hardware faults, such as a defective step-up converter, affected components on the circuit board are expertly replaced.

Finally, a comprehensive functional test is performed to ensure seamless communication between the control unit and the vehicle. All repairs come with a 12‑month warranty.

What shipping options are available at Airbag24?

For sending your control unit to Airbag24, you can either ship it yourself free of charge or arrange a convenient UPS pickup. For return shipping, free standard options are available, along with faster express and cash‑on‑delivery services from UPS; alternatively, self‑pickup is also possible.

For the initial shipment, you have two options: You can securely pack the removed control unit and send it to us yourself—this is free of charge. Alternatively, you can arrange a UPS pickup at your preferred location.

After successful repair, we’ll ship the unit back to you. Standard UPS shipping (1–3 business days) is free; for an additional fee, we also offer UPS Express shipping (1–2 business days). Both options are available with cash-on-delivery. Of course, you can also pick up your repaired unit directly from our premises.