0X930937: Passenger Belt Tensioner Circuit

Circuit fault

What 0X930937 means

The passenger belt tensioner sits in the right side retractor and fires at the start of a crash to take slack out of the belt before the airbag ever touches the occupant. Its circuit is monitored continuously. When the module reads chassis ground on one of the two wires, it can no longer confirm the charge is intact and isolated, so it logs 0X930937.

On the passenger side the wiring runs down the right B-pillar and under the right front seat, and it shares that space with seat occupancy sensing and seat motor wiring on well equipped cars. More harnesses in the same area means more chances for a pinch during seat removal, and it also means more connectors sitting low enough to catch water from a wet carpet.

Common causes

• Harness pinched under the passenger seat rail or damaged by seat travel
• Corroded tensioner connector from water in the carpet or a leaking door or window seal
• B-pillar trim installed with the tensioner wire trapped against the pillar structure
• An internal short in the tensioner charge inside the retractor
• Terminals damaged during seat belt or seat replacement
• Aftermarket seat or upholstery work that disturbed the restraint harness

Crash data or hardware fault?

Treat 0X930937 as a snapshot of the wiring right now. The ACSM takes the reading, files it, and drops it once the circuit is healthy again. Crash data is a permanent entry with no relationship to current wiring. It marks a deployment event, and clearing codes with a scan tool does not remove it from the module.

Does our reset clear it?

The honest answer is that a reset does nothing for a live short. The module measures the passenger tensioner circuit again at the next start and logs the same fault. Repair or replace first. A fired passenger tensioner is a different situation, since the belt has to be replaced and the module usually holds crash data, and mailing us the ACSM is how that record gets cleared.

Which makes throw it

BMW vehicles store 0X930937. It is read through BMW hex diagnostic software on models using an ACSM with pyrotechnic belt tensioners front and rear.

What to do next

Move the passenger seat through its full range and watch for the fault to appear or disappear, which catches a pinched harness quickly. Then inspect the connector at the retractor and the carpet underneath for moisture. A tensioner that still reads shorted once it is unplugged from the harness needs a new belt assembly, and we stock genuine OEM BMW passenger belts. Related codes: 0X930931, 0X930949, B1355.