I have a 2002 f150 with a 4.6 and service engine light came on, showed po125 coolant fine, have heat, brought ectsensor could not find it on truck so took to ford place said they put it on for $35, then later said i did not have one , i needed head temp sensor for $420 ,does this sound right

 

I'd try a thermostat before anything else.

 

To replace the Cylender Head Temp sensor, the intake manifold, etc need to be removed, so it's probably a fair price for a shop to charge.

 

I have good heat ,does that matter