2009 V6 mustang
 

Why does the temp gauge go to hot only sometimes and then comes back to the normal? Is it sticking??

welcome....

Welcome to MF! :) ...could be a thermostat...car over heating?

welcome to MFs... and i say.. delayed electric fans & coolant flow!

welcome to the site.

Just to be sure, check the underside of your oil cap for evidence of water (baby poop/puke yellow color) and your coolant for signs of oil. If either, then you have a head gasket problem. If not, then I'd begin checking out if it's mechanical (thermostat, fan...) or instrumentation (gauge...).

The '09 4.0L is identical to the '05, '06, '07, '08 and '10 4.0L so you have a lot of experience to draw from here.

Sounds like possibly a thermostat if the car isn't overheating!

Had the same problem with my 05.Checked temp with a pyrometer and it was fine ,ended up getting instrument cluster replaced.You do need to check for mechanical issues but do not spend money unless you can diagnose problem.Should still be under warranty.

Thanks everyone.