0X930961: Rear Left Belt Tensioner

Circuit fault

What 0X930961 means

The rear left tensioner is built into the retractor for the driver side rear belt, mounted in the C-pillar or the seat back structure depending on the model. It pulls belt slack at the beginning of a crash exactly like the front units do. Its circuit is monitored, and a reading of chassis potential on either wire causes the module to store 0X930961.

Rear tensioner faults trace back to the trunk and rear seat area more often than to the tensioner itself. The harness leaves the module, travels under the carpet along the sill, and rises behind the rear seat or into the pillar. Anything that involves folding seats, hauling cargo, replacing a battery in the trunk, or installing audio equipment can reach that run.

Common causes

• Harness pinched behind a folding rear seat back or under a seat cushion latch
• Cargo or amplifier installation damage to the wiring under the trunk or rear carpet
• Corrosion at the tensioner connector from a trunk or taillight seal leak
• An internally shorted tensioner charge in the rear retractor
• C-pillar trim reinstalled with the wire trapped against the body structure
• Terminals bent or backed out during rear seat or belt replacement

Crash data or hardware fault?

This code tracks a live reading, so it answers to repair work. Once the rear left circuit measures correctly, the ACSM stops storing it. Crash data does not answer to repair work at all. It is the permanent record written when restraints deploy, and it stays in the module until the module itself is reset or replaced.

Does our reset clear it?

Resetting the module will not un-short a rear harness. Repair the circuit, verify the reading, and clear the code normally. A rear tensioner that actually fired is a replacement item, and a car in that condition almost always has crash data locked in the ACSM as well. That stored record is what our mail-in reset service removes, once the new belts are installed.

Which makes throw it

BMW is the make for 0X930961. The code comes from BMW hex diagnostics and applies to BMW models with pyrotechnic tensioners on the rear belts.

What to do next

Fold the rear seat forward and check the harness where it crosses the seat back latch and the pillar, since that is where cargo and seat movement do their damage. Inspect the trunk floor for water if the connector looks corroded. A tensioner reading shorted with the harness disconnected means a new belt assembly, and we can supply genuine OEM BMW rear seat belts. Related codes: 0X930955, 0X930979, B1346.