The sensors in the seats are their twofold one for seatbelt warning and second for telling the airbag a seat is being sat on , apparently the passengers airbag will not deploy if it does not sense a weight on the seat be warned it can go of if in an accident you have a heavy weight on the seat .Someone on this VW forum had theirs deploy because of a handbag on the seat tricked the sensor . As others suggested battery off and leave then the lights on as it will drain off any residual charge or even leave the ignition on after disconnecting will do the same . Also worth noting do not turn on the car or reconnect the battery until all connections are reconnected or it may trigger a fault warning .