STS with STS Air Bag Light
 

I have a 2007 STS with 58.7k. The airbag light has been on for at least 3 years. I knew dam well it was passenger side. I got a hold of a $200.00 code read/reset (Zurich (ZR13) tool and yup indeedy it's the passenger side presence senor. I pulled codes B0081-39 internal malfunction and invalid data B0081-71. Resetting doesn't help. Reseating the connectors (as many as I could find) didn't help. I have to get this fixed to sell this car otherwise it's a piece of junk because most states now will fail a safety inspection. I got a hold of a presence sensor bypass for the STS and it didn't help. Same codes and erasing didn't help, they come right back. So I'm going to hang on tight and take it to the dealer this Saturday unless someone here has words of wisdom for me.

The car is at the dealer now.
$169.00 for a diagnostic test and they said the passenger side presence senor needs to be replaced.
They ordered one $800.00 with labor, installed it and it didn't fix the problem. Now they want to replace the module that it talks to, another $800.00. What's the chance that actually two modules are bad? I'm just not comfortable with the way things are going and this so called flow chart. $1600 worth of modules are bad? Nobody knows if it's going to work. What about the cable between the two modules.