I have a 1990 190E. Same thing. The sending unit is cheap and easy to replace. You can go one of two ways. If your guage works after the replacement, then that was the problem. Unfortunately, if you wind up like me, after replacing the sending unit it still didn't work, then it's the guage. Dealer wants $$$$ for the whole dash assembly. A dismantler can give you just that guage that has the temperature (and I believe the gas, etc) on it for less. I hope Benzmac can give you (and I) some pointers on replacing it ... i.e. how do you remove the dash, etc.