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Discussion Starter · #1 ·
My 1st winter with my lly. During summer it always ran 187-190 on cts. Now it will climb to 170-172 then drop back to 165-168 around town. So cold engine protection always on and fuel mileage is about 13mpg. Should I put a winter front on? Or replace thermostats? No other issues
 

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Discussion Starter · #2 ·
Located in Massachusetts. So hasn't been that cold yet.
 

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I put my winterfront on around freezing temps. If towing I keep an eye on the temp gauge. If you Don't know how old the coolant is you may as well change it and install new t-stats st the same time.
 

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Thermostats. I went through two NH winters with the same issue. Changed out the stats, back to 181-183°
 

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I was also running the gm grill cover before stats, now I'm not
 

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Discussion Starter · #6 ·
Thanks I will replace them
 

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I would also suggest sticking with the stock temp 180/185 stats, the factory ones made in Japan. I know there are different temps to choose from
 

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Mine was running 179-189 today in 45°f
 

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Discussion Starter · #10 ·
thanks! t-stats changed and temps back to 179-185 in in cold temps.
 

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Good to hear
 

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My truck runs 150F-160F while in the 30s.
 

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I couldn't get my temp over 170 in the middle of the day here in the south a few weeks ago, it was normally 160; changed my tstats with GM stats and its running 180-189*
 

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160 is fine.
 

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It's supposed to run around 180. Probably another old thermostat issue.
 

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P0128 copied from another site:

This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat.

Read more at: http://www.obd-codes.com/p0128
Copyright © OBD-Codes.com

How you can say '160 sure that's fine' is beyond me. That's like yah the ecm is just lying to you, no prob
 

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Furthermore up here where the temps get below freezing and even below 0, we need heat, and the engine needs to be at a proper temp to run it's best. Probably not as much of an issue in Texas
 

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Mine runs around 160 in the winter due to short driving and have never had a CEL as a result. The engine would likely have to run a lot lower than 160 to trigger the fault. I understand your concern about heat, but the engine will be fine at 160.

People never realized their vehicles had so many problems before internet forums!
 

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Discussion Starter · #20 ·
also if your running that cool the engine is super inefficient and burning a ton of fuel.its bad all around. makes no sense to not fix.its simple and cheap.i was getting 11-12 mpg running at 165 deg.
 
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