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temp issue

1322 Views 15 Replies 3 Participants Last post by  Regert
I'm new to the 6.4L and have a code for "temp sensor out of range to low" coolant bottle is at normal level and truck runs good. could this be a t-stat or maybe just the temp sensor out of wack? anyone run in to this?

Thanks Regert
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What is your temp at? There are some calibration issues with them not warming up quick enough throwing that code. Mine does it occasionally, and now I have determined that my thermostat is stuck open since it never gets above 180 unless I'm towing.
I plugged my scanner in and it showed 69 degrees so I'm thinking t-stat as well. if I beat on it it'll warm up to normal but when I run normal it cools right off. Where's the t-stat on these motors they hard to get to?
69 degrees? Where are you located, it's warmer than that outside here in Oklahoma. lol When I start mine, it usually reads ~10 warmer than the outside temperature, and within 5 miles of driving, its up to around 130-140ish. Once I hit the highway, about 5 miles down the road it's up to around 175-180. With a working thermostat it should be around 195. Let it idle and it will cool off some, but still stays easily above 150 unless it's around freezing outside.

The thermostats are in the lower radiator hose connection in the side of the block. I haven't changed mine yet, but they look to be buried in there pretty deep and not much room to work in. There are videos of them being changed, and after things are moved out of the way, they aren't too difficult to do.
I know the temp is low maybe the temp sensor is effed. today the gauge didn't move till i put about 40km on it then I push it and it came up some more but not to the operating temp it usually sits at.
What is the ambient outside air temp where you are located? If the gauge never moved, I would lean towards sensor. My gauge always starts moving once the engine is near 100 degrees or above and it will get that high within 10-15 minutes just idling.
today its about 22 out and I'm in Canada
Ahh, ok, so you are probably talking Celsius. 22c=71f, and 69c=156f so you aren't too far off then. Sounds like yours is doing exactly what mine is, so it very well could be thermostats.

Here is a video. Not super detailed, but shows the important parts:
lol yes sorry. Think I'm going to farm out the t-stat and coolant change, it looks like a bit more then I want to tackle. #rather spend time with the family then a shower of
Yep, I don't blame you. I have a few other things I want to upgrade so I'm going to do them all at once. Probably have to wait until closer to fall before I dig into mine though.
what coolant is the best to run, I read that the 6. 0l run specail fluid not sure on the 6. 45min tho
T-stat is a bear to get to unless your EGR is deleted, then it's just forearm deep behind the fan under/behind where the vertical EGR cooler tracked. It's located just under the terminal end of the Upper radiator hose. You have to remove the degas bottle, battery & tray, and radiator hose.
Peak Final Charge is what I use. I've heard lots of good about it, but the key is no silicates. There are others out there that people use, just don't pick anything that looks good. Ford Gold, Final charge, one of the Zerex type (can't remember what it was called) all seem to be decent.
what coolant is the best to run, I read that the 6. 0l run specail fluid not sure on the 6. 45min tho
I use Peak's Final Charge. I ditched the Ford Gold with my last flush. Very happy with it thus far. You can look up threads on here with lots of discussion about Ford Gold or making to leap to use other ELCs. Peak claims the Final Charge coolant is formulated for all heavy duty engines and created from over 10 Billion miles of testing. Look it up under commercial grade coolants.
And agree with kleake- whatever you choose, make sure you research it pretty well.
Thanks for the info guys, I'll be using the Peak Final Charge and Propably tackle it in the fall might do a egr delete as well.
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