2004 Mercedes CLK-Class Owner's Manual - Page 308

Practical hints What to do if ...? Problem Possible cause The yellow "CHECK ENGINE" malfunction indicator lamp comes on while driving. There is a malfunction in: The fuel management system The ignition system The emission control system Systems which impact emissions Such malfunctions may result in excessive emissions values and may switch the engine to its Limp-Home Mode (emergency operation). The fuel cap is not closed tightly. Your gas tank is empty. Suggested solution Have the vehicle checked as soon as possible by an authorized Mercedes-Benz Center. An on-board diagnostic connector is used by the service station to link the vehicle to the shop diagnostics system. It allows the accurate identification of system malfunctions through the readout of diagnostic trouble codes. It is located in the front left area of the footwell next to the parking brake pedal. Check the fuel cap. After refuelling, start the engine three or four times in succession. The Limp-Home mode is canceled. You do not need to have your vehicle checked. ? 308