[Guest]

This is part of the water outlet housing.

I'm pretty sure the pieces go together like in the picture below, but I'm not sure, as the valve/bullet looking piece, doesn't look like it allows any fluid through it.
The hole, where it looks like it should go in looks like fluid passes through it. (worded kinda weird).

If you have this part of the water outlet housing and are able to check, or if you just know, please let me know.

 

[AustinJ]

I have a spare water outlet housing (the whole thing) sitting in my garage, I just checked it, and it doesn't look like that piece goes there. (it isn't there on mine, anyway) I also didn't see any other pieces that look like that on any of the other sensors and whatnot in either piece of the housing, although I don't have the cold start time switch thingy in there anymore. (used it to plug a hole in my Koyo rad.) Looks like the mystery continues... :doh: