Coolant temperature display & intermittent engine chugging

Hello. I have a Mercedes E350. A week or so ago I started to get coolant temperature warning lights (frequently but not continuously). I topped up the radiator with a glass of water but the warning light is still lit up, and today the engine started "chugging" intermittently. Are the two symptoms connected?
Thanks for any input.
Reply to
Sebastian Drayton

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.