Checking the coolant level
WARNING Risk of injury due to overheated drive system
If you open the bonnet when the drive system has overheated or during a fire in the engine compartment, you could come into contact with hot gases or other escaping operating fluids.
Before opening the bonnet, allow the overheated drive system to cool down.
In the event of a fire in the engine compartment, keep the bonnet closed and call the fire service.
WARNING Risk of burns from hot component parts in the engine compartment
Certain components in the engine compartment can be very hot, e. g. drive system and radiator.
Allow the drive system to cool down and only touch the component parts described below.
WARNING Risk of injury due to moving parts
Components in the engine compartment may continue running or start up suddenly, even if the ignition is switched off.
Make sure of the following before performing tasks in the engine compartment:
Switch the ignition off.
Never reach into the danger zone surrounding moving components, e.g. the rotation area of the fan.
Remove jewellery and watches.
Keep items of clothing and hair away from moving parts.
WARNING Risk of scalding from hot coolant
If you open the cap when the drive system is at normal operating temperature, you could be scalded.
Let the drive system cool down before opening the cap.
When opening the cap, wear protective gloves and safety glasses.
Open the cap slowly to release pressure.
Park the vehicle on a level surface.
Check the coolant temperature display in the instrument cluster More.
The coolant temperature must be below 40°C.
Slowly turn cap 
anti-clockwise to release overpressure.
anti-clockwise to release overpressure. Continue turning cap anti-clockwise and remove it.
anti-clockwise and remove it. If the coolant level is below the marker bar 
, visit a qualified specialist workshop, e.g. a Mercedes-Benz Service Centre. Only have coolant checked or refilled at a qualified specialist workshop.
, visit a qualified specialist workshop, e.g. a Mercedes-Benz Service Centre. Only have coolant checked or refilled at a qualified specialist workshop.