Mercedes-Benz

Warning/indicator lamps

Problem	Possible causes/effects andsolutions
The red coolant warning lamp is lit while the engine is running.	Possible causes: The temperature sensor is malfunctioning The coolant level is too low The air supply to the radiator is obstructed The radiator fan is faulty If there is an additional warning tone, the coolant temperature has exceeded 120 °C. WARNING Danger of burns when opening the bonnet If you open the engine bonnet when the engine 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 engine to cool down. In the event of a fire in the engine compartment, keep the engine bonnet closed and call the fire service. Stop the vehicle immediately in accordance with the traffic conditions and switch off the engine. Do not continue driving. Note the messages on the multifunction display. If the coolant temperature display is at the lower end of the temperature scale: Consult a qualified specialist workshop. or Exit the vehicle and keep a safe distance from it until the engine has cooled down. Check the coolant level . Make sure that the air supply to the radiator is not obstructed. Avoiding high loads on the engine, drive to the nearest qualified specialist workshop. In doing so, ensure that the coolant temperature display remains below 120 °C.

Problem

Possible causes/effects andsolutions

The red coolant warning lamp is lit while the engine is running.

Possible causes:

The temperature sensor is malfunctioning
The coolant level is too low
The air supply to the radiator is obstructed
The radiator fan is faulty

If there is an additional warning tone, the coolant temperature has exceeded 120 °C.

WARNING Danger of burns when opening the bonnet

If you open the engine bonnet when the engine 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 engine to cool down.

In the event of a fire in the engine compartment, keep the engine bonnet closed and call the fire service.

Stop the vehicle immediately in accordance with the traffic conditions and switch off the engine. Do not continue driving.

Note the messages on the multifunction display.

If the coolant temperature display is at the lower end of the temperature scale:

Consult a qualified specialist workshop.

Exit the vehicle and keep a safe distance from it until the engine has cooled down.

Check the coolant level .

Make sure that the air supply to the radiator is not obstructed.

Avoiding high loads on the engine, drive to the nearest qualified specialist workshop. In doing so, ensure that the coolant temperature display remains below 120 °C.