I thought I'd check as many sensors as I could before popping the engine back in. Seems like a reasonable plan. There are like twenty separate temperature sensors on this engine! OK, there's six but still........

Fortunately Audi stamped the range or trigger point on them. Well, most of them.

I didn't check change over temperature. I just had hot water or no water but I think I proved they all do something so I'm going with that.

This one tested good too but didn't want to go home :(

Need to find a seal washer for this one. How hard could that be?