18/05/2026
A "Top Up Engine Coolant" or "Check Coolant Level" warning light on your Mercedes means the fluid is unsafely low, placing the engine at serious risk of overheating. Topping up requires parking on a level surface, letting the engine cool completely, and filling the reservoir with water until it reaches the fill.
How to Safely Top Up Your Coolant
Let the engine cool: Wait at least an hour or let the car sit overnight. The cooling system is highly pressurized; opening the cap while the engine is hot can cause severe burns.
Locate the reservoir: Open the hood and find the coolant expansion tank. It is usually a small, translucent black or white plastic container with a warning symbol (or thermometer/radiator icon) on the cap.
Open slowly: Place a thick towel or rag over the cap and unscrew it slowly counter-clockwise to safely release any remaining pressure.
Check the level: Look inside the reservoir. You will typically see a black or white plastic marker or tab. The coolant should be flush with the bottom of this mark.
Top up the fluid: Pour in a 50/50 mix of distilled water and approved Mercedes-Benz coolant. Do not use tap water, if possible as it can cause mineral buildup and corrosion.
