I drive a 1998 c280, and intermittently on long highway/road trips, my dash will beep at me and give me "-2.0q" along with the oil light. Some times it goes away, some times it doesnt. This usually only happens on longer trips (and I live in a hilly area, so sometimes these contain some pretty long descents/ascents, but the light will still come on on long straight flat drives too). However, it never shows anything other than 2 quarts low, either the "-2.0q" or nothing at all.

Most of the time this happens, I will pull over to a nice flat spot to check my oil, only to find out its perfectly fine.

Do the oil level sending units ever go bad in these cars? Anyone know what the problem could be?

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I love my cars to death but my wallet sure doesn't.

i have seen several that were defective and would cause the same problem you describe, on that odel they are fairly easy to change, it is located on the drivers side of the oil pan and is held in by two 10mm bolts, it is best to do this at your next oil change when the pan is empty