Intake manifold gasket leak? (Never heard of a heat sensor). Many possibilities.
first of all, do you have the right thermostat? ie: winter, summer. if so i would get the radiator checked, it may be getting pluged.
We don't know what relay you are referring to. Check your thermostat and radiator fan. Fluch out your cooling system.
It could be you thermostat Have you have already checked oil level, and/ot changed oil recently Exaust restrictions can cause overheating
I would suggest you replace the thermostat, and flush the cooling system. Also check the radiator fins and see if they are clean and free of debris.
The IMPELLER on the water pump.The MIXTURE of Anti-Freeze to Water mixture.Blown head gasket.Correct TIMING.the FLOW on the Radiator that U already checked...
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It could be any number of things, but I'd check for bad fan relay or fuse, sticking thermostat, blocked radiator or blown head gasket.
Your car is starting to overheat or your thermostat is going out. Get it checked.
This question is not complete. . Need to know if you've replaced radiator, thermostat, hoses etc. Are you asking this question *after* yo checked the thermostat, changed, added or drained the system?
have the engine timing checked. if the timing is wrong the engine will overheat, are you loosing coolant?is the fan working, is the water pump working?
check your fan clutch if its weak it will overheat
Check all the wiring and the Thermal Relay for the fan.