Red overheating light 2015 Mitsubishi mirage - UPDATE: coolant was low

[Top_Fuel]

...There -IS- definitely coolant loss. The overflow tank went from full to almost half full in approx 4 days of driving 40 miles a day.

I would just watch the level in the coolant bottle closely for the next couple of weeks so you can document any further coolant loss. Be sure to check the level every day under the same conditions every time...like first thing in the morning before the engine has run.

The dealership did everything you could reasonably expect them to do at this point. If the coolant loss continues, then there are other things that can be done...like checking for a blown head gasket. But that's a huge leap forward...there's no need to hit the panic button on that, yet.

It took me months to find the coolant leak in my wife's 1999 Eclipse. It had a hairline crack (from age) in the plastic radiator tank. It would only weep a few drops under perfect conditions. I could smell it, but never see it. Then one day when I had the hood up (and the engine was hot), I literally saw droplets of coolant forming on the surface of the tank...like they were appearing from nowhere. I almost had to get a magnifying glass out to see the crack where it was leaking. I'm just using this as an illustration to let you know that these leaks can be tough to track down.

Did I mention getting a Scangauge?