2005 Mercedes Benz E500

Computer problem
2005 Mercedes Benz E500 V8 Two Wheel Drive Automatic 63000 miles

Anyone with an e-class mercedes ever heard of an error for replacing the gas cap? I am getting this message all of the time, even after replacing the gas cap. I have now started to notice it is being triggered by one of two things. Either the fuel level is right in between 1/2 and 3/4 or when the A/C is on. Strange but true. Anyone familiar?
May 18, 2009.

It sounds like there is an EVAP leak somewhere in the system. This is the system that prevents gas fumes from being lost into the atmosphere. What I recommend is having the EVAP system fogged. A mechanic will actuall force fog at a low pressure into the system. If there is a leak, the fog will come out and you will see where the problem is. Without having it fogged, you will go crazy tring to find the problem.