High pressure tells me of a possible head gasket problem. Have the cooling system pressure tested by a reputable garage; this will answer some questions.
it has a cracked head The above answer would be an extreme condition to cause this problem. Usually a car overheats because of either low coolant level or a stuck or bad thermostat.
Possible causes include an inoperative radiator fan and low freon levels.Possible causes include an inoperative radiator fan and low freon levels.
The problem you seem to be having is the cooling temp sensor. It controls the fan speed which has two speeds. Try that.
I have the same problem and I hope I Can get an answer.
Possible trany cooler leak
I had this problem ....Head Gasket or radiator cap
pollution and possible vermin infestation
coolant draining back into resivoir or possible air pocket
It's possible that you may have a faulty thermostat.
There are many possible causes of overheating. They include low coolant, inoperative radiator fan, failed water pump, missing belts, restricted radiator, failed head gasket.
Possible causes for overheating include failed serpentine belt, failed water pump, internal or external coolant leak, restriction in the radiator, or inoperative radiator fan.
a hole in the radiator