I'm not thinking it'* a pcm. Not without looking at what the pcm sees for a temperature. The dashboard'* are known issues. I can take a picture of my car running for ya if you'd like proof. Theres no way my oil pressure is 80psi or that my voltage is 18volts. I've confirmed both via scanning and manual pressure gauge. I've also seen many cars where the temp was in the red and the temp via pcm wasn't....
So here'* how I'm gonna lay out my advice. Take it. I've given many good suggestions, asked for a picture of the sensor you replaced etc and so far... you haven't provided anything back to help out. Therefore while I'd like to help, it'* very difficult when I'm blind and have no information.
If your engine is an L36, which can easily be verified by pictures, looking at the side of the block where it says "Series II" or any of a few other ways.. then there is no sensor on the passenger side. If your engine is Series I then there were two sensors. They were identical, one was under the throttle body, the other was on the driver side back of the intake manifold.
Like I said though,..as soon as you help us with information/pics, we can help you better.
00 Regal GS: All kinds of cool stuff.