Bought a used 2014 F150 5.0 4x4 XLT
takes forever to warm up when cold outside, getting a code 128
I replaced thermostat with a motorcraft 190 deg. thermostat.
Let it warm up, made sure it opened, filled coolant, has no air in it and
has been about a month since i did it. It still has same problem. Takes forevor
to warm up. After a few days will set a code 128. Should be the only thing to
cause this. What am i missing?
My previous 2012 F150 did same thing and replacing thermostat fixed that one.
Any ideas? Thx

 

How about a bad coolant temperature sensor maybe.

 

Since it still takes a long time to get heat and if there is no other coolant issues like leaks or noise in the cooling system I would try another OEM thermostat. As a note my 2014 EB also takes longer than I think it should to throw heat but a P0128 is 90% of the time a thermostat. Does your gauge correspond to the heat?

 

Since it still takes a long time to get heat and if there is no other coolant issues like leaks or noise in the cooling system I would try another OEM thermostat. As a note my 2014 EB also takes longer than I think it should to throw heat but a P0128 is 90% of the time a thermostat. Does your gauge correspond to the heat?

 

I had a person come to me with his Ranger would not get up to temperature and he had the thermostat replaced and coolant flushed. I pulled the thermostat and found it was installed upside down...... just a thought.

 

Yea, responds to heat. Once its hot, like on a normal day, the gauge reads halfway also checked with scanner. Heater works like it should
when the coolant temp gets up to temp. And no, its not upside down, actually its impossible to install backwards. I guess ill get another Motorcraft
and try again, This will be the 3rd one. Should be the only answer but hard to believe. Thanks

 

If there are no other codes you have to cover that base with a new motorcraft tstat. Are you buying them from a dealer if so and the parts personal are good guys they could warranty it for you.

 

Only other thing I can guess is cooling fans staying on all the time.

 

Still would not cause that as the motor coolant itself is not hot, hasnt entered radiator yet if t/stat works right.
Bought t/stat from Rock Auto, Motor craft.

 

...or thermostat stuck open.