So earlier today I was idling in a parking lot and I heard a noise under the hood but it stop and about 4 minutes later temperature gauge was close to the top. I turned the car off and waited for the temperature to go down to limp it the car home. Once I started to drive it the temperature went back down no a normal operating temp but when I started idling at a stop light the gauge started to read high again. I don't understand what could be causing this issue. It is a 2012 g37x coupe. 145k

Sorry if this thread is in the wrong spot I am new here.

 

I'd drain & fill w/ new coolant and thermostat may need replacement. Welcome to the site btw

 

Alright, new thermostat ordered and I will replace the coolant today. Hopefully that solves it.