Hello Im new to this page but i have a problem with my 2003 g35 coupe about 4 weeks ago it started to over heat got a new thermostat installed it myself but than when i tired to take it home it started to over heat again so once i got home i left the car sit for a whole day and when i started the car back up it didn't overheat again but now my cooling fan wont stop spinning and they told me it was the temperature sensor so i went and got a new sensor but they still wont stop spinning. what do i need to do now car runs and drives fine but the fan just will not stop

 

Have you read and followed the FSM?

http://www.nicoclub.com/FSM/G35/Coupe/2003/co.pdf

See page CO-24

"7.Remove thermostat and thermostat housing.
Do not disassemble thermostat and thermostat housing.
Replace them as a unit, if necessary."

With a fourteen year old vehicle I not only would replace the thermostat and housing as well as the water pump, radiator cap, hoses and coolant.
Use factory OEM parts.
Do a pressure test

Telcoman