Hey there Scotty,
I live in Atlanta, GA and I have a high mileage 2011 3.5L Ecoboost F150 with 185K Miles. I bought it used in 2018 with 145K. No major issues at all, truck runs and shifts great. I never changed the transmission fluid and not even sure the previous owners did. However, I do change my oil regularly (unrelated to the main topic).
Anyways, recently during the colder months, I've been getting error code P0128 (Coolant Thermostat below thermostat regulating temperature). I've changed out the following myself: Thermostat, CHT (cylinder head temp) sensor, done a coolant flush (using Genuine Ford VC-1 Premium Cooling system flush) using all Motorcraft OEM products. After all these repairs, I clear out the code using my scanner, but after a few days when it's still cold out, the stupid code still keeps coming back. Additionally, I've seen slight decrease in my mpg. Can you help me with this problem please?
Thanks!
KingBeef
Well either you got a bomb thermostat and it's not working right or you're sending unit for the temperature to the computer is gone bad and it's giving bad data
Thanks for the reply. I changed out the thermostat and the truck is blowing hot heat. Additionally, I just replaced the sending unit (cylinder head temp sensor, passenger side). Should I try to replace the thermostat again?