Other Fuel System Hoses Lines/piping, And Fittings problems of the 2005 Mercedes Benz E500

Emission system has multiple issues over time that cause check engine ligjt to engage. Problem s range from, gas cap to fuel tank parts to valves to carbon canister issues. All issues occur when vehicle is stationary and in motion. No impact.

Possible gas leak. . . Strong gas smell on each fuel up. Stays around until tank drops to about half full. No other signals and Mercedes Benz had me replace the gas cap. Nothing changed. Please advise.

Driving on street--instrument cluster lights up red saying "check fuel tank cap"--drive to park turn off engine--check fuel cap -check engine light comes on-- same exact thing happened 5 days later.

Fuel pump / sender fuel leak under rear seat. Has gas smell after getting gas. Check engine light comes on with gas cap warning light constantly, especially if add gas more than 3/4 tank. Over the years (I still own the vehicle), even with 1/2 tank gas the gas cap warning light would come on from time to time, especially in hot weather. Dealer hasn't been able to fix issue since I bought car as cpo in 2008. They told me to replace gas cap. Replaced, no impact. I opened up the rear seat and can see gas stains in the fuel sender/pump cap area with some residual gas.