CLK 200 Engine management light coming on.

I would replace the gas cap as a first step. John

After 24 years of Mercedes-Benz Dealership Parts experience I can say with confidence that these vechicles are technilogically too far advanced for "seat of your pants" diagnosis.

I have seen many Factory Trained Mercedes-Benz Technicians struggle with diagnostics even when using factory provided and updated diagnostic equipment.

It is not always cost effective to avoid the Dealership Service Department.

Dealer Service Departments generally have much more access to barrow and test replacing multiple components from their Parts Departments until they discover the right combination to effect the repair without selling the Customer several non-returnable electrical items.

My advise, take it to your local reputable Mercedes-Benz franchised New Car Dealer and request an itemized estimate of repair.

If they can't figure out what's wrong, no one can.

Les