I was thinking the service processor route next, it has been awhile since I have used it - thanks for the notes and link to docs...
We do not have any hardware support on the system, it is scheduled to be replaced in a few months so I just need to squeeze a bit more life out of it.
When I look at the location codes for the P730
here, it shows the sensor should be at "Un -D1"; looks like that's the whole control panel that slides out - i'll try re-connecting that part.
Interesting that I was not able to see in "diag" a way to select and test the thermal sensor, it was not in the list.