Hello All,

I am posting this new thread after looking through similar threads and not getting a correct answer.

What is happening with my '06 f150 V6 is that the temperature gauge does not go any higher than 1/4. I plugged in my scanner and the P0128 code came up stating (coolant temp below thermostat regulating temp). I changed the thermostat twice and the housing for it. I just got a brand new radiator and the fluid was recently flushed and refilled. I am not losing any fluid. I was told by a mechanic it can be the heating core. My question(s) is the mechanic bull****ting me to gain some extra cash. What else can it be? The ECT temp is reading 57 celsius/ 134 fahrenheit. I read that it should be close to if not 200 fahrenheit. If anyone has any ideas please help me out before I start spending close to $900 for labor on a heating core.

 

Temp sensing element.

 

Would that mess with the gauge and when I turn the heat on no warm air comes out.

 

In order to determine what is going on, you need to actually measure the thermostat housing with an IR thermometer to see how hot it actually is. You may have an issue with the replacement thermostats (especially if not Motorcraft parts), the thermostat installation, or the inferred temperature reading which is actually from the CHT sensor assuming that you posted your question in the correct section. Since you failed to explicitly identify in your post what you are working on, there's some ambiguity involved.