To my surprise the CEL is gone after I left the car unused for a day. I scanned the OBD II codes and there is none. I have done nothing except taking a look under the hood.

Now I am confused, was it a temporary issue or a quirk in the electronics or self-healing EGR?

Anyway

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1996 E320 since 1/16/08, 171K miles as of Feb 2011

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1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE