930A1C airbag control unit fault

What does error code 930A1C mean?

Error code 930A1C indicates a specific communication fault in the airbag control unit. This error frequently occurs in BMW M5 models (F90, G90) and signals that the control unit is no longer communicating correctly with other vehicle control modules. The root causes are often stored crash data or an internal hardware defect.

Technically speaking, this means a disruption in data transmission on the vehicle’s CAN bus system. The airbag control unit (often referred to as the ACSM – Advanced Crash Safety Module) enters a safety mode or becomes completely blocked, especially if so‑called crash data has been saved in its internal memory after an accident.

This condition not only prevents the airbag system from functioning but also hinders communication with diagnostic tools. Simply clearing the fault memory is usually impossible, as the blockage lies at a deeper, hardware‑level stage.

How do you recognize error 930A1C?

The primary and unmistakable symptom of error 930A1C is the permanently illuminated airbag warning light on the instrument cluster. Additionally, diagnostic tools may fail to establish a connection with the airbag control unit, making precise fault analysis more difficult.

The airbag warning light does not turn off after starting the vehicle. This is a clear indication that the system has detected a critical fault and is non‑functional in an emergency situation. Consequently, the vehicle reports a failure of the occupant protection system.

Another technical symptom is complete loss of communication. When attempting to read the airbag control unit using a diagnostic tester, the connection fails. The module does not respond to requests, pointing to a severe internal fault or lockout.

What causes error 930A1C?

The most common cause of error 930A1C is crash data stored in the control unit following an accident, which locks the module. Other reasons include internal hardware defects in components such as microcontrollers, damaged connectors due to corrosion or moisture, and issues with seat occupancy detection.

After an accident, irreversible crash data is written into the control unit’s memory. These data block normal operation and communication, and cannot be erased using standard workshop diagnostic tools. This is a manufacturer‑specified safety measure.

Defective internal components represent another key cause. Faulty memory chips, cold solder joints, or malfunctioning microprocessors can disrupt internal data processing and lead to a complete breakdown in communication.

External factors such as moisture and water ingress can also trigger this error. Corrosion on connectors or on the control unit’s circuit board interrupts electrical connections and causes communication problems. Likewise, issues with the seat occupancy mat—temporarily disrupted by dampness—can activate this error code.

In which vehicles does error 930A1C occur?

Error code 930A1C is particularly relevant for high-performance BMW models. At Airbag24, our repair focus for this specific communication fault centers on BMW M5 series, where this error code appears most frequently.

At Airbag24, we specialize in repairing error code 930A1C for the following specific models:

BMW: M5 F90 (2018–2023), M5 G90 Sedan (from 2024)

How does repair work at Airbag24?

Professional repair at Airbag24 begins with the submission of the removed control unit. First, a thorough analysis and reading of the internal memory take place. Next, stored crash data is cleared, defective electronic components are repaired, and the device is tested for full communication capability.

Once the faulty airbag control unit arrives at the workshop, a comprehensive diagnosis is performed. This includes visual inspection for external damage such as moisture or corrosion, as well as reading internal fault logs and memory contents to pinpoint the exact cause.

The central step is professionally resetting the control unit. Any existing crash data is erased, and the unit is restored to factory settings. If the diagnosis reveals a hardware defect, affected electronic components—such as memory chips or microcontrollers on the circuit board—are expertly repaired or replaced.

Finally, the repaired control unit undergoes an extensive functional test to ensure seamless communication with other vehicle systems. All repairs at Airbag24 come with 2 years' statutory liability for defects.