Left Rear Occupant Detection Sensor Range/Performance Problem

The car has a sensor under the left rear seat that detects if someone is sitting there. If it's not working right, it can cause problems with the airbag system.

The airbag control module sees inconsistent data from the left rear occupancy sensor. It expects a certain resistance value when someone is seated, but it detects an out-of-range value.

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 11. Inspect the wiring and connectors of the left rear occupant detection sensor for damage or corrosion. Decision: If damaged, repair or replace. If good, proceed to step 2.
2. 22. Measure the resistance of the left rear occupant sensor with a multimeter. Expected value is between 2.5k-5.0k ohms when undamaged and seats are empty. Decision: If outside expected range, replace the sensor. If within range, proceed to step 3.
3. 33. Check for fault codes in the airbag control module with a scan tool. Decision: Resolve any other codes present before fixing B1939.

• Faulty left rear occupant sensor
• Damaged wiring or connector to the sensor
• Faulty airbag module
• Calibration issue in the occupant detection system

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