The sensor for the outside temperature in located in the lower bumper just inside of the left fog lamp. It's black plastic about 3/4" in dia. with a pointed end. Start there to check for the problem. Also there are bulbs which illuminate the instrument cluster. If the lower left one is burned out, the temp is very difficult to read especially if the illumination is turned down. Repeatedly press the '+' button to see if there's a reading. To remove the cluster (friction fit) you need a set of cluster hooks.

A more serious problem is 'missing pixels'. A few people have worked on the ribbon cable which connects to the display with varying levels of success. If necessary there are a couple of companies which do repairs.

The left fog light is an issue for W210's as well as the left stop light. Actually, getting false positives on burned out bulbs is pretty common. If the light is out but the bulb and fuse are ok, try cleaning the contacts. Next examine the socket and housing for signs of overheating. You'll need to remove the front anti-noise panel. If the socket is shot, MB makes a repair kit which includes the socket and a pigtail to splice into the harness. Although, some newer models have a quick connect.

Good luck.

It doesn't seem like a sensor issue since there is almost no display. But I would assume that would be much easier to fix, so I'll start there (when I have time ). I doubt it is the instrument bulb being burnt out because I can clearly see one line sometimes but nothing else.

Thanks for the info on fog lights.

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2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD