Aumakua

just wondering if this has happened to anyone else out there and how you fixed it. My engine light came on and I noticed I was getting about 25% worse MPG than I normally get. I brought the car in and the dealer told me the fuel was too lean, they checked pressure and a few other things and said it was fine. They reset the engine light. The next morning the light is back on (hadn't refueled yet) and the car is now vibrating when idle (can feel it in steering wheel and seat). Called the dealer back and he told me it could take up to 2 new tanks to get rid of the bad fuel, I am half way through a new tank and still no change. He also said the engine light should go off on its own once the fuel cycles through in a couple days... Should I take this to a different dealership?

Yuille36

It could very well be your purge valve, that is what happened to several of us. It caused a lean condition, and thru a Check Engine Light (CEL). They kept my car for several days to diagnose the issue, and ultimately replaced the bad purge valve, with a new one. Their is a Technical Service Bulletin (TSB), out of this. Here is my post on the subject:

https://mbworld.org/forums/c63-amg-w...ine-light.html

Or no can do a search on purge valves.

C63newdude

It happened to me. Here is my thread:

https://mbworld.org/forums/c63-amg-w...ult-codes.html

Dealer also questioned the quality of the gas at the time of the survey.