The code I had from the OBD-II was P0705 "Transmission Range Sensor Circuit malfunction (PRNDL Input)"
The gear selector position sensor on the SAAB 9-5 is attached to the top of the transmission and can be reached by removing the battery and battery tray.
eeuroparts.com seems to have the sensor listed as the Neutral Safety Switch (NPN Switch).
You will need:
A socket wrench and extender
Disconnect the positive and negative battery cables with the 13mm wrench. Remove the nut and brace behind the battery with the 13mm socket. Lift out the battery. Remove the four 10mm screws and remove the battery tray.
You should be able to reach the 17mm bolt and other connectors on the gear selector position sensor from here.
I cleaned everything I could, sprayed a little WD-40, and once everything was back in place I sat in the car and pulled the gear selector from park all the way down to 1st and back up to park. I did this several times fairly rapidly. This gives me a month or two of relief from the issue.
Here is a great write up about the gear selector position sensor.