Coolant temperature sender location

[d-a-n]

I've run the paperclip test on my 1997 N/A EP91 and it's flashed up 2 codes - a 12 and a 22.

Don't know how to tackle the 12 so the thing I'm going to sort first is the 22 code - coolant temperature sender (or coolant temperature sensor?) but I don't know where it is on this engine. Anyone able to help/add pictures so I can whip it out and try a new one. My thinking is a response to the saga below (reading is optional)

The engine management light comes on briefly (5-10 seconds) as the coolant gets up to normal temperature, then it goes out again. While driving it sometimes comes on again, at times it's stayed on for over a minute then it goes out again. Sometimes it doesn't even come on at all - I thought at first this may be something to do with the ambient temperature but I've driven it in all conditions and it seems to be totally random.

Any help would be appreciated!