Low Engine Temperature

[cgraves817]

2016 Tahoe LTZ
I have noticed for awhile engine temperature won't raise above 170 degrees. Didn't bother me till it got cold outside. With the engine temperature so low I get only lukewarm heat.
I also occasionally get the annoying zero temp reading and the engine fans run. I have already replaced the temp sensor.
Thinking thermostat now????

 

[L8T BURB]

I realize this will sound odd, but all you need to do is replace the thermostat with a GM Genuine part. The issue is that the thermostat gets stuck partially open and will not allow the engine to consistently get to full operating temperature. Once you replace the thermostat, you'll need maybe a half gallon or so of Dexcool, as you'll lose a little when you remove the old thermostat. Once the repair is done, use a pocket scanner or similar to clear any stored engine codes. Typically this failure will store a code of "coolant temp below threshold". Sometimes it won't actually illuminate the check engine light, but it will store the code. The engine fans running and temp gauge dropping to zero is due to this stored code causing the system to run in fail safe mode. Without clearing the stored code, the symptoms may persist for a short period after the thermostat replacement. Scanning and clearing the codes when replacing the thermostat is the sure bet for a successful repair.

Funny thing, people on this forum are still convinced that this is a temp sensor issue. I bet $100 if you replace the thermostat and put your OLD temp sensor back in, you'll be good to go. The new temp sensor is fine of course, but it's not the root cause of the problem you're having.

 

[strutaeng]

You can always remove your thermostat and dunk it in an old pot of boiling water and see it open. It's a slow action though.

However, if it's not warming up, I think that means that it's open all the time, no? Or maybe partially open as @L8T BURB suggested. When it's running at operation temperature, does the coolant hose feel warm?

I had a thermostat fail once on my 99 Silverado and in the winter, there was simply no real heat. A new thermostat is easy to replace and inexpensive. I would just get a new GM Genuine and pop it in there.