24464019

I added coolant last year spring, the indicator was between middle and plus end. But today I found it is at minus end.
Does this mean my car have a coolant leak? The temperature is at 200F stably during driving.

I tried to have a check around my engine bay but didnt see any liquid or violet spot.

Shuga

Sometimes you just need to add coolant, it's been over a year it's not uncommon. Keep an eye on it. Also make sure your coolant cap is very tight.

djdonte

The coolant level will vary with temperature. To be sure you need to check it completely cold. Sometimes a little is lost to evaporation but its a sealed system. Very small leaks, like leaks that take a year to show will not cause wet spots or drips. The coolant weeps out somewhere and causes sludge or dried white residue. Look for this on all your connections. Sometimes you can smell the sweet coolant smell. You didnt say if you have a 970 or 971 but I believe one or more of the 970 engines have a coolant fitting that is pretty much glued in and is a point of failure. I would not panic yet, just keep a closer eye on it.

Shuga

That was only the 970's not 970.2's. And if OP doesn't see a puddle underneath the car, I wouldn't be concerned at all.

PandaSPUR

If the coolant level display works like the oil level display, the range of the display is from "needs more coolant" to "full" rather than empty to full.

I recently learned the oil level display represents just 1 quart.

Anyway, agreed with the others, you're probably fine. Top it off and carry on.

24464019

Added 500ml(distlled and antifreeze) and it went from minus to middle
So @PandaSPUR is correct, minus only means need more, not empty.
(and I bought 2 gallon antifreeze for free shipping and 250ml per year, then it should be enough for 36 years of refill lol. gonna sell the second unopen gallon)