Problems with the engine

Problem Possible causes/consequences and Solutions
The engine does not start. The starter motor can be heard. • There is a malfunction in the engine electronics.
• There is a malfunction in the fuel supply.

the engine again, turn the SmartKey in the ignition back to position 0 Before attempting to start the engine again, turn the SmartKey in the ignition back to position 0 or press the Start/Stop button repeatedly until all indicator lamps in the instrument cluster go out.
again. Avoid excessively long and frequent attempts to start the engine Try to start the engine again. Avoid excessively long and frequent attempts to start the engine as these will drain the battery.
If the engine does not start after several attempts:
specialist workshop, e.g. an authorized Mercedes-Benz Center. Consult a qualified specialist workshop, e.g. an authorized Mercedes-Benz Center.
The engine does not start. You cannot hear the starter motor. The on-board voltage is too low because the battery is too weak or discharged.

the vehicle. Jump-start the vehicle.
If the engine does not start despite attempts to jump-start it:
specialist workshop, e.g. an authorized Mercedes-Benz Center. Consult a qualified specialist workshop, e.g. an authorized Mercedes-Benz Center.
The starter motor was exposed to a thermal load that was too high.

cool down for approximately two minutes. Allow the starter motor to cool down for approximately two minutes.
again. Try to start the engine again.
If the engine still does not start:
specialist workshop, e.g. an authorized Mercedes-Benz Center. Consult a qualified specialist workshop, e.g. an authorized Mercedes-Benz Center.
The engine is not running smoothly and is misfiring. There is a malfunction in the engine electronics or a mechanical component of the engine management system.

accelerator pedal slightly. Only depress the accelerator pedal slightly.
immediately at a qualified specialist workshop, e.g. an authorized Have the cause rectified immediately at a qualified specialist workshop, e.g. an authorized Mercedes-Benz Center.
Otherwise, non-combusted fuel may get into the catalytic converter and damage it.
The coolant temperature gauge shows a value above 248 °F (120 °C). The coolant level is too low. The coolant is too hot and the engine is no longer being cooled sufficiently.

and allow the engine and the coolant to cool down. Stop as soon as possible and allow the engine and the coolant to cool down.
Observe the warning notes as you do so and add coolant if necessary. Check the coolant level. Observe the warning notes as you do so and add coolant if necessary.
    See also:

    Checking the coolant level
    Only check the coolant level when the vehicle is on a level surface and the engine has cooled down. Turn the SmartKey to position 2 () in the ignition lock. On vehicles with KEYLESS-GO, press ...

    Cleaning the seat belts
    – Use clean, lukewarm water and soap solution. Do not clean the seat belts using chemical cleaning agents. Do not dry the seat belts by warming them above 176 °F (80 °C) or placing them ...

    Special seat belt retractor
    All seat belts except the driver's seat belt are equipped with a special seat belt retractor. When activated, the special seat belt retractor ensures the seat belt will not slacken once the ch ...