B0079: Driver Seat Position Sensor Circuit

Circuit fault

What B0079 means

A driver sitting close to the steering wheel needs a different deployment than a driver sitting well back, so GM monitors where the seat sits on its track. The sensor is usually mounted on the seat rail, reporting a forward or rearward position to the sensing and diagnostic module. A circuit reading outside the expected range, whether open, shorted, or implausible, sets B0079.

Seat rail wiring lives a hard life. The harness has to flex through the entire travel of the seat, thousands of times, and the connector at the floor gets disturbed every time the seat comes out for carpet work or interior repair. Add the debris that collects under a seat and the water that reaches it from a wet floor, and most of these faults turn out to be wiring or alignment rather than a dead sensor.

Common causes

• A broken or stretched conductor in the seat rail harness where it flexes with travel
• The sensor knocked out of alignment with its target magnet or bracket
• A floor connector left unlatched or damaged after seat removal
• Corrosion at the sensor or floor connector from wet carpet
• Debris packed around the sensor blocking the target
• A failed sensor that no longer changes state

Crash data or hardware fault?

Measurement happens continuously on this circuit, so B0079 is a live fault and not stored crash data. Fix the wiring or the sensor and the entry stops returning. Crash data is written when airbags deploy, it records an event rather than a measurement, and no scan tool can clear it from the module memory.

Does our reset clear it?

Erasing the code does nothing for a seat harness, and the module logs the same fault as soon as it checks again. Repair or replace the sensor and its wiring first. Our mail-in reset service applies to modules locked by stored deployment data, which is a separate situation from a seat position circuit. Call 501-988-0611 if you are not sure which one your vehicle has.

Which makes throw it

Cadillac, Chevrolet, and GMC use B0079 for the driver seat position sensor circuit. The three brands share GM restraint diagnostics, so the code reads the same way across them.

What to do next

Run the seat all the way forward and all the way back while watching live data, because a sensor that never changes state is either disconnected or out of alignment with its target. Look under the seat and confirm the sensor and bracket are still where they belong. Repair any broken wiring at the rail with a proper crimp and enough slack, since that harness keeps moving for the life of the vehicle. Related codes: B0074, B0080, B1028, B009F.