so your yellow airbag plug is unplugged and there is nothing to plug it into and the Subaru dealership said it wasn't a problem? There's something really wrong there. Is everything plugged in the correct place? The drivers side should have 2 plugs on the seat on the bottom. One is white which is for the seatbelt, the other is yellow which plugs into the airbag. Your passenger side im pretty sure has 2 or 3. One for the airbag, one for the occupancy sensor and I'm not sure if on an 06 if it has a seatbelt sensor. If you said you tried a airbag from another car that you knew worked and that didn't fix it then you have ruled out that. So it has to be a wiring issue. How many wires, plugs are their on your driver seat?