What does it mean?
B1390 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Passenger Seat Track Position Sensor Short .
Symptoms
- SRS lamp on with a passenger seat position fault stored
- The value on the scan tool sits at one extreme and does not follow the seat
- Passenger airbag deployment force falls back to its default setting
- Fault often appears after the seat has been removed, refitted or the carpet cleaned
- No effect on running, starting or driveability
Likely causes
- Under-seat loom crushed between the passenger seat rail and the floor pan
- Signal wire chafed onto the sensor ground or an adjacent circuit inside the same loom
- Spilled liquid or wet carpet reaching the passenger seat connector and bridging the pins
- Sensor damaged internally after being struck by cargo pushed under the seat
- Terminals spread or bent after the seat connector has been unplugged repeatedly
- Loom trapped when the passenger seat was bolted back down
- Airbag control module measuring circuit fault
How to fix it
- Look at the live passenger seat track value and slide the seat to see whether the reading moves at all
- Power down the restraint system safely and wait the specified discharge time
- Unplug the sensor and inspect both connector halves for moisture, salt tracking and spread terminals
- With the sensor unplugged, measure the signal wire to ground; a low reading confirms a shorted harness
- Inspect the loom along the seat rail and under the seat pan for flattened or trapped sections
- Repair the damaged loom section and reroute it clear of the rail
- Replace the sensor if the wiring is clean, then confirm the value changes smoothly through the full seat travel