So today, my high temperature light came on. This time I had my scan tool on and saw the temperature. The coolant temperature was over 250 degrees. I was able to slow down, get the temperature back to around 220, turn off the truck and get the light to come off.

The things I have done to far to fix the problem with no results:

Change Cylinder head sensor
Oil change and filter
New fan and fan clutch
Tested the thermostat and working properly

So why is my coolant getting over 250?

Any suggestions?