0X930904: Driver Stage 1 High Resistance

Circuit fault

What 0X930904 means

The ACSM expects the stage 1 inflator to measure within a narrow resistance band, typically a couple of ohms of squib plus a small amount of wiring. When the value climbs above that band, the module logs 0X930904. A completely open circuit reads as high resistance too, so the code covers everything from a slightly dirty terminal to a wire that has broken in half.

High resistance faults are often intermittent, and that is a useful clue. A connector that is latched but sitting on a bent terminal will read fine at rest and fail when the wheel turns or the car goes over a bump. That behavior separates a connection problem from a truly open inflator, which reads high all the time no matter what the vehicle is doing.

Common causes

• A driver airbag connector not fully latched after steering wheel or clockspring service
• A clockspring with a broken conductor in the ribbon, so the circuit opens at certain wheel positions
• Corroded or oxidized terminals in the airbag connector or the yellow inline connector
• A spread or backed-out pin at the ACSM connector
• An inflator that has failed open inside the driver airbag module
• A repaired or spliced section of firing circuit wiring with a weak crimp

Crash data or hardware fault?

Real time measurement is what puts this in the live fault category, so 0X930904 is a live circuit fault and not stored crash data. It disappears on its own when the resistance comes back into range. Crash data is the permanent entry made after airbags deploy, and no scan tool can clear it. The two live in different parts of module memory and they call for different repairs.

Does our reset clear it?

A reset does not lower resistance. The ACSM measures the loop again within seconds of the next start and writes the same value back if nothing changed. Find the open or the bad connection and fix it. Where the module also holds deployment data from a crash, our mail-in reset clears that record, and it is usually part of the job on a car where the driver airbag already fired.

Which makes throw it

BMW vehicles set 0X930904. The code comes out of BMW hex diagnostics and applies to models running an ACSM restraint controller.

What to do next

Remove the driver airbag and reseat both the connector at the bag and the yellow connector behind the clockspring, because an incompletely latched plug is the most common cause and it costs nothing to rule out. Then measure the loop with the wheel turned to several positions to catch a broken clockspring conductor. A reading that stays open at the airbag itself means the bag needs replacing, and we carry genuine OEM BMW driver airbags. Related codes: 0X930902, 0X930905, B1901.