check in the radiator by taking the cap off (cold engine) then let the engine idle and see if the coolant is flowing try revving the engine see if its flowing like it should kinda like suck the coolant down.
then if thats flowing nicely
then remove your fan belt wiggle the water pump pulley it should be firm and not play also turn the pulley if its good it will move freely and smotthly.
Look for leaks as well as it normally leaks if there's something wrong with the water pump.
Check you thermostat if its operating as spec
Did you change you coolant and let the air pockets out?
Check temp sender unit, maybe faulty and the wiring