Thanks for your input. Actually the gas cap was the first thing I checked. I also looked for any disconnected vacuum lines. I did get an appointment with Leith Mercedes in Raleigh. I was given an appointment for the day following my call, they started work almost immediatly upon my arrival, and found the source of the problem in a fuel system purge valve and a cannister purge valve. The light stayed off on my return trip home to MI today. Based on my experience, I would return to Leith for service should the need arise.