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Codes on my truck

1619 Views 10 Replies 6 Participants Last post by  cart7881
So my check engine light keeps coming on so i put my dads OBD2 scanner on it and it read a PO128 undefinable code. and i was jw if any of yall would know what it might be.:355group:
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i have a haynes manual here and it says colant thermostat (coolant temperature below thermostat regulating temperature) so id say check you anti freeze or possible replace you thermostat
i have the red anti freeze in my truck idk how big of a difference it really makes but it is starting to get real cold here in the mornings but i have noticed that the temp. has been running a whole lot cooler then normal. and the heater doesnt blow as hot.
There are just too many Threads here to reference. Click on the "Search" box at the top of this page, in the middle, and enter "P0128".
I quick search on Google found over 90 references on this site in 0.36 seconds...
Let me google that for you...

1. Check Coolant level. 2 Thermostat defective. 3. Cooling Sensor defective.

The Stant 48718 XACTStat 180 Degrees Fahrenheit Thermostat this is the only 180° thermostat available for these trucks. The dealerships only sell the newer replacement 192°F thermostat now. The 192°F stat will run just under 3/4, while the 180°F stat will running just under half way mark on the gauge.
Mine when i first got it ran at the first big line in any tempature. now it runs under that when its cold outside and runs just under the half way mark when its hot out but has never over heated
I saw the thermostats on RockAuto were 180. Is 192 better?
I think Gates makes a 180° thermostat for the 355s, part number 34045.

Gates 34045 - OE Type Thermostat Water Outlet Assembly | O'Reilly Auto Parts
Agreed I have this one.
Gates 34045 or Stant 48718 will fit the 2005 2.8 I4
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