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:

    Front air bags
    The front air bags increase protection for the driver's and front-passenger's head and chest. Driver's air bag 1 deploys in front of the steering wheel; front-passenger front air bag 2 depl ...

    Lights
    Display messages about LEDs: This display message will only appear if all LEDs have failed. Display messages   Cornering Lamp Left or Cornering Lamp Right Possible causes/consequences an ...

    Transfer case
    This section is only valid for vehicles with 4-wheel drive (4MATIC). Power is always transmitted to both axles. Performance tests may only be carried out on a 2-axle dynamometer. The brake ...