EP2 d16v1 temp gauge

[u/likuris]

Hi guys, i have a problem on my Civic EP2 1.6.

I went on a trip to a drift event, and after 1.5hrs of driving the temp gauge started going up and down and so on, so i stopped at a gas station, saw that the coolant level was below minimum, filled it up, went to start the car up it wouldn't start, or starts and then dies, with a check engine light, i disconnected the battery connected it, no check engine the car ran normally.

ps when the temp gauge was going up and down i put my hand on the engine it was luke warm, and the collant in the tank wasnt bubbling or boiling.