Hot temprature gauge

#1

I drive a vt commodore and when in idle the temprature gauge moves to hot and when the car is moving the gauge is fine. What is the problem?

#2

Did you check the coolant level, both in the overflow tank and in the radiator (when cold)?

Does the fan run when the car is idling?

Overheating an engine can be very bad for it, so I’d avoid driving the car until this is fixed.