Is it part of the injection?

[dylant]

I own a w124 260E '88 and i noticed next to the top cover between the air filter right on the engine are three switches, the one in the middle is the temp I know but the one closest to the windscreen has melted and the two electrical pins attached to it have melted off too. I went to mercedes just to check first and they say it controls the fuel injection at different tempretures, it looks about one inch in diameter and is a copper and green colour, is this correct? Is it a very important part or not and if I get a new one is it easy to replace my self?
Much Appreciated for anyones advice!