Hi, I have a 2004 Mercedes CLK270CDI. In the past two weeks the car has been going into limp home mode if left to idle at traffic lights. The engine check light doesn't come on. By switching the ignition off and on again the car drives perfectly again. There are no strange knocks or any other symptoms. I though originally it may be the Air Mass sensor and replaced this but this has not sorted the problem. I'm thinking now it may be the EGR. The car has been plugged into the diagnostics and nothing shows up.