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Fan still running and temp not moving off 160


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I had issues with the fans staying on full speed intermittently after changing headlights. People seem to think unplugging the mass airflow sensor can cause this fan issue and I needed to remove the airbox for the headlight change. What finally fixed the full speed fan issue was changing the thermostat. Its been approximately 3 months since changing the t'stat and have not had the fans kick on high speed again.

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My temp sensor got all wacky right before my battery died. Was working fine before the battery died. The dead battery and wacky sensor caused the fans to get all crazy too. I replaced the battery and that fixed the fan issue but my temp won't go past 160 now either. Was thinking about replacing the sensor but now I'm thinking of replacing the thermostat. I'm close to 200k miles on the original water pump so thinking I should go ahead and do the temp sensor, thermostat, and water pump. Does anyone know if Part No 12685257 includes everything? Looked at pics online and looks like it does but can't tell for sure.

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  • 10 months later...

I still haven't found a resolution to this problem. It's not the temperature sensor or the thermostat. The problem only occurs when it's cold outside. Temperature stays pegged at 160, fans run on high. Clearing the code makes the fans turn off and gives an accurate reading of the coolant temperature. Again, this only happens with an ambient temperature below maybe 55*F. Problem comes back every winter, goes away in the summer. 

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1 hour ago, Ole Bill said:

I still haven't found a resolution to this problem. It's not the temperature sensor or the thermostat. The problem only occurs when it's cold outside. Temperature stays pegged at 160, fans run on high. Clearing the code makes the fans turn off and gives an accurate reading of the coolant temperature. Again, this only happens with an ambient temperature below maybe 55*F. Problem comes back every winter, goes away in the summer. 

 

 

What code(s) are you getting?

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  • 2 weeks later...
On 1/8/2022 at 11:39 AM, JohnThomas70 said:

I replaced the coolant temperature sensor with an AC Delco sensor and the thermostat but the temp is still remaining on 160 and the electric fan is  programming up to high and staying on.  Is there a reset that I’m missing? 

I had the same problems a few months ago. I replaced the thermostat temperature sensor housing, drained the fluid going to it, put in new fluid, and after an hour it should go back to normal,

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  • 8 months later...

I've been after this problem for quite a while and dealer couldn't solve it. Temp gage falls out ac goes off fans go on high check engine comes on.

Turn off ignition restart sometime it resets sometime not. Lately temp goes up overheat message on dash then back to normal and falls out again  I changed coolant sensor and checked connector no difference. Noticed battery ground was not fully tight with 10mm nut tighten all the way. Also noticed voltage fluctuations when temp gage and ac falls out. I cut a copper pipe to act as a sleeve on battery post and was able to snug cable. Problem solved

 I believe it was the voltage drops from lose battery cable.

 

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5 hours ago, David C Snyder said:

I've been after this problem for quite a while and dealer couldn't solve it. Temp gage falls out ac goes off fans go on high check engine comes on.

Turn off ignition restart sometime it resets sometime not. Lately temp goes up overheat message on dash then back to normal and falls out again  I changed coolant sensor and checked connector no difference. Noticed battery ground was not fully tight with 10mm nut tighten all the way. Also noticed voltage fluctuations when temp gage and ac falls out. I cut a copper pipe to act as a sleeve on battery post and was able to snug cable. Problem solved

 I believe it was the voltage drops from lose battery cable.

 

It seems that many problems on these trucks happen as a result of a loose or defective battery cable and/or ground issues. I think this should always be a first step when trying to troubleshoot...

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  • 3 months later...

I really found this hard to believe but I had 3 temperature sensors stop working over the past 6 months and I humored myself and cleaned the terminals to my battery.  (Which is original 2016 and passed the batter check).  The terminal connection was tight but there was quite a bit of dust I knocked off with a wire brush.  Reconnected and temperature sensor now works fine with no errors for the past 4 weeks.   
 

seems to have worked….   

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  • 1 month later...

2015 Silverado 5.3.  Same issue.  It was my battery.  Had turned over slow a couple of times over the last month as I hadn't driven it every day.  Today turned over slow.  Pulling up to a location I was was wondering where this noise was coming from, like is someone using a blower, or is there a big truck near me?  Turned off my truck and got out to hear it coming from my truck.  Same noise on my drive home, stopped at O'Reilly, changed out the battery, temp gauge at 160 all the way home (was 50 today here) thought that was strange, but got back in it an hour later and drove around, no fan noise and temp back to just under 210 like normal.

In my case 100% the battery.

Edited by Snowman1234
Update - 2 weeks later radiator fan running again loudly while driving and staying on for 5 minutes after turning off truck. Weird that new battery seemed to resolve the issue temporarily. Anyway, new gm thermostat Wednesday.
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