Id say top it off again if it can be and start checking for small leaks at hose connections, radiator (hope not) there is many of them. Fuel heater, aux water pump, heater valve (monovalve), reservoir hoses etc to name a few. Looking for wetness or crusty white residue caused by evaporated coolant. Those would be a simple start and what I would do. Could be a faulty switch or elctrical circuit if you are in fact full of coolant always when it lights up.

Arlo

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W211 E550
HVAC/R Certified Technician