P0128 - Engine Taking to Long to Heat Up

[benreed405]

Whenever the weather gets colder I get this code that says my engine is not heating up fully. The temp gauge also stays below mid line and when accelerating drops to almost 1/4 of the gauge. I have tried a coolant flush, checked coolant levels, and replaced the thermostat twice. Any other suggestions for troubleshooting?

 

[BMW2FORD]

That's usually from a stuck open thermostat but do you know what type and / or temp thermostat was installed or have a picture of the last one removed? Only other thing that helps warm up the engine are the radiator shutters but that just assists and really the T stat does almost all the regulation. Maybe the shutters are stuck open? Take a look through the front grills with the climate control system off while the truck is cold started and idling and see if they are closed. There usually open when the car is turned off then adjust to what's needed as you start then drive.

 

[LokiWolf]

Owned it new, or bought used? Wondering if the Thermostat was replaced with a lower temp one. Common in the Tuner crowd.

 

[99WhiteC5Coupe]

Whenever the weather gets colder I get this code that says my engine is not heating up fully. The temp gauge also stays below mid line and when accelerating drops to almost 1/4 of the gauge. I have tried a coolant flush, checked coolant levels, and replaced the thermostat twice. Any other suggestions for troubleshooting?

Did you use the correct OEM Motorcraft thermostat, or aftermarket?

 

[osteodoc08]

Could be a coolant temp sensor as well. Unlikely to be a thermostat if all 3 are giving same readings (original and
2 replacements)

 

[Soliyou]

Mine is starting to take long time to warm up... and If I turn on the heat, the temperature will actually drop while driving!

I think that these engines have a heater control valve that directs the coolant to the heater core if heating is needed. May be this valve is stuck open?!!

I think it is part #: JL34-18495-BB (YG857 (18495)): https://parts.ford.com/shop/en/us/climate-control/heater-repair-parts/valve-13291383-1

From the parts diagram, it seems it is easy to be reached without too much effort (see 18495 in the figure below)

 

[FlyBry]

A Little info, I look at my SCT Tuner every morning at startup, and am thoroughly impressed with how fast this V6 heats up. This AM Outside Air + Engine Coolant = 61 deg. Before I can get out of the driveway, engine temp is already 140 deg+. Get to the end of the block, and the engine is 150 deg+.

 

[OverlandExpy]

Got the same code last weekend while doing a snow camping trip. Hoping the only reason it threw the code was because it was so cold outside and I had the heater on. 2004 EB. Anyone else ever have this happen?

 

[benreed405]

Owned it new, or bought used? Wondering if the Thermostat was replaced with a lower temp one. Common in the Tuner crowd.

I bought it used and replaced the thermostat twice with OEM factory part purchased from the dealership.

 

[benreed405]

Did you use the correct OEM Motorcraft thermostat, or aftermarket?

Yes, I purchased from the dealer a factory OEM motorcraft part.