I just reinstalled my 1997 1.8T engine after frame shop removed it for frame straightening after collision. They did not have ability to reinstall, and of course, did not label anything. I'm almost finished with the major stuff, but I have a strand of two wires with a 1/2" long chalk-gray metal sensor sticking out of a 19mm nut and dark bronze course threads that look like it goes into cast iron and gets very hot. I can't find the hole it goes in. There was one just like it on the exhaust pipe to catalytic converter. The one I have loose is on the driver's side at firewall, bundled with other wires and only has about 12" of length from the bundle strap. Any ideas as to where it attaches?

 

Pics would help a lot.

 

After I snapped a pic to send you I got to poking around the Cat converter and found that this is the post cat convert ox-sensor. Thanks anyway.