Steve,

I just went through this with my 1998 E300D TurboDiesel. Mine said something about engine electronics, and over the phone the service person told me it was most likely the air mass flow sensor. I took it in under warranty and they changed it on the spot after doing a quick diagnostic check. It took about an hour or so. I asked if it was ok to drive with the light on, and the service guy said it probably wouldn't hurt anything if I did not notice a performance difference, depending on what the actual failed part was. An air mass flow sensor must not be vital because the car ran pretty good for several hundred miles. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)