External temp reading glitches

[fuseman]

I've just bought a 1994 E320 cabrio. The external temp reading is all over the place - goes up and down 10 degrees every few seconds. It isn't a big deal but if I wanted to sort it is this likely to be a problem with the external sensor? If so where is it sited, can you get replacements, are they pricey and are they easy to fit?

Any advice welcome.

[Dieselman]

Probably but check the cabling first. It lives poking out of the front grille below the bumper.