It is a rather common issue...at least I hear a lot of people complaining about it. Replacing the sensor requires removing the seat and pulling it apart(upholstery) I hear it's costly.
Has anyone here used a Seat sensor Bypass? They sell them online and fix the issue(Airbag-light will still have to be reset). The only difference is the Airbags will deploy on passenger side even if nobody is sitting there during a wreck. Cheap fix and much better than riding with Airbag light on, which will prevent airbag system from deploying at all(from what indy mechanic told me).
If anyone has used a sensor bypass please give us some feedbak.
2003 Z4 2.5i Silver/Black