I got the waterpump and timing belt done, stripped a bolt taking the thermostat out, got it situated I'm going to replace the coolant temp sensor while I'm in there, does the one in the housing control the gauge? Or is it the one behind the head

 

The TP3909202 pdf from that site has 159 pages, if you don't have it then your download did not complete or you downloaded the wrong file.

Per that document, the gauge sensor (7/7) is in the front of the engine, the water temp sensor for EFI (7/16) is on the back of the head just above the water pipe.

I would not replace either before proving they are defective, this is very easy with ohmmeter. Aftermarket replacements from the parts store often have something wrong with them!

By the way if you do not want to buy the bolt sealant from volvo, for the water pump bolts, an equivalent is Loctite 545 (Permatex has an equivalent too.) I bought the 545 from mcmaster-carr.

 

Well got the oxygen sensor done still having issues with the 112