What does it mean?
B1786 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Occupant Classification Sensor Front RH Collision Detection .
Symptoms
- Airbag warning lamp permanently on with occupant detection disabled
- Passenger airbag indicator frozen in one state and no longer following the occupant
- The code cannot be cleared and reappears as soon as the ignition is cycled
- Zero or calibration routine aborts with an error
- Live weight data for that corner is implausible or pegged at a limit
Likely causes
- Genuine impact to the vehicle or a sharp blow through the seat cushion
- Excessive load such as someone kneeling on the seat or heavy goods placed on the cushion
- Seat mishandled during removal or refitting, taking its weight on the cushion instead of the frame
- Load cell or its bracket bent, giving a permanent over-range reading
- Sensor wiring damage causing a signal spike the module treats as an impact
- Seat frame twisted or the rail bent, forcing load into the front right corner
- Occupant classification module fault
How to fix it
- Read all occupant classification and restraint codes and review the event and freeze frame data
- Establish the history: recent accident, seat removal, heavy load on the seat or anyone standing on it
- Empty the seat completely and inspect frame, rails, brackets and sensor mounts for distortion
- Check the sensor lead and connector for crushing, chafe and corrosion that could create a false spike
- Try the manufacturer's zeroing or calibration procedure and record whether it completes
- Where the latched event cannot be reset, replace the affected sensor or the seat frame assembly exactly as the manufacturer specifies
- Recalibrate afterwards and confirm correct classification empty and with a known weight