314 Practical hintsWhat to do if …?Problem
Possible cause
Suggested solution
?
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 opera-
tion).
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 read-
out of diagnostic trouble codes. It is lo-
cated in the front left area of the 
footwell next to the parking brake pedal.
The fuel cap is not closed tightly.
Check the fuel cap.
Your gas tank is empty.
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.