Over heating

If the gauge goes way up and then drops fast then I would suspect the thermostat but if the coolant level is really low that also could be the cause. What ever you do, fix the leak before you damage your engine.

lightning bolt normally means bad alternator. Turn your car on and disconnect the battery. If the car shuts off you need a new alternator if not I would either take it to advanced to have them hook it up to the computer or get a code reader

Do not listen to SBUSHIK1116 above, Never start the car and disconnect the battery unless you want to damage your engine computer which costs a LOT!

FULL_OF_REGRETS, I have never damaged my engine doing this. Several people and mechanics I know have done this and not one has created a problem. When they checked my alternator they did the same thing and the car shut off. They put a new one in and I had 0 problems. Your name says a lot. The last person I would listen to is someone who is full or regrets. Just saying.

A battery test is easy to perform and can be done at home. First, open the hood and start the car. While the engine is running, remove the negative cable from the battery. If the vehicle stalls or dies, the alternator is likely bad........ all you have to do is type how do you know if an alternator is bad into google and the first 10 pages I clicked on alllllll say the same thing. So do your research before you tell someone it will destroy an engine computer when that is clearly false.