0X930905: Driver Stage 1 Lines Coupled

Circuit fault

What 0X930905 means

A firing loop has a high side and a low side, and the inflator sits between them. The module relies on that separation to measure resistance. When the two wires touch each other anywhere along the run, the measured resistance collapses toward zero and the module can no longer tell whether the inflator is even present. That reading gets filed as 0X930905.

The failure is usually mechanical. Two conductors running side by side in a flat ribbon or a tight harness bundle rub against each other until the insulation between them is gone. The clockspring ribbon is the classic location on a driver airbag circuit, since it winds and unwinds through the full travel of the steering wheel thousands of times over the life of the car.

Common causes

• A clockspring ribbon worn through between adjacent conductors
• A crushed section of harness where both firing wires were pinched together
• An airbag pigtail trapped behind the bag during reinstallation
• Corrosion or moisture inside the connector bridging the two terminals
• A shorting bar in the connector that stayed engaged instead of releasing on latch
• An internal short across the inflator winding inside the driver airbag

Crash data or hardware fault?

A live wiring condition is what the ACSM is measuring during every self test, which places it well outside the crash data category. The entry disappears once the two wires are separated again. Crash records do not work that way. They are written at the moment of deployment and remain in module memory regardless of the state of any circuit.

Does our reset clear it?

Nothing about a reset separates two shorted conductors. The module measures the loop again at the next start and stores 0X930905 again. Replace the damaged clockspring, harness section, or airbag, then clear the system. Our mail-in reset service comes into play when the ACSM is locked by deployment data, which is common on a car where the driver airbag has already fired.

Which makes throw it

BMW uses 0X930905, and it reads the same across BMW models with an ACSM restraint controller. The hex format comes from BMW diagnostic software rather than the generic OBD code set.

What to do next

Disconnect the airbag at the wheel and remeasure. A short that clears with the bag unplugged tells you the problem is inside the airbag or its pigtail, and a short that remains sends you to the clockspring. Also verify the connector's shorting bar released properly when the plug seated, since a stuck bar imitates this fault exactly. We stock genuine OEM BMW clocksprings and driver airbags. Related codes: 0X930904, 0X930907, B1C49.