Fan still running and temp not moving off 160

[sprky]

2016 GMC Sierra fan blowing, temp gauge at 160 and I have Engine warning light on for P0156, P0157 (O2 sensor codes nothing to do with engine temp). Clear the ODB codes,  temp gauge corrects and blower stops. One reason has to be electrical. I am not a mechanic by a long shot! Just changed the sensors and still throwing the codes. Bummin'!

[troy tremaine]

Let me correct my last post.  This temporarily made the issue go away but I ultimately think it cleared the computer memory.  Issue came back again.  The issue is the thermostat.   It’s a simple replacement and takes about 20 minutes.   I replaced and all issues went away and I also noticed my heat in the cabin got significantly hotter which is also a sign of a bad thermostat.  I would replace both the thermostat and sensor since they’re in the same spot.   

[Dena]

Replaced battery recently. Replaced sensor and thermostat but fans still coming on high and no fluid moving through hoses. Could it be a bad new thermostat? Should we have scanner hooked up to see what codes come up?

[mikeyk101]

2 hours ago, Dena said:

Replaced battery recently. Replaced sensor and thermostat but fans still coming on high and no fluid moving through hoses. Could it be a bad new thermostat? Should we have scanner hooked up to see what codes come up?

Did you replace with OEM or aftermarket sensor and thermostat? I had bad experience several months after replacing my thermostat with aftermarket. A Motorad to be specific. Replaced it again with an OEM but went with a lower temp (194⁰) one and it's been fine every since.

[GregGoBlue]

My 2016 GMC Sierra with the 5.3L has done the fan on high for 3 straight years. I live in Michigan and the only time the fan turns onto high is in the Spring and Fall time periods when we temperatures between 40F & 60F degrees. So any time its in the 40's or 50's it seems to happen, then in the winter when its teens, 20's and 30's it never turns on. The same goes for the summer when its 70's, 80's, 90's it never turns on. I have replaced my coolant sensor with an AC Delco OEM unit. I disconnected the battery for 10 minutes and the problem temporarily went away, but came back two days later. Next I've purchased a thermostat, I plan to change it out this week. I am slowly doing one thing at a time to see what the root cause was for my situation to hopefully help the next person. I have no codes being thrown, there is no check engine light coming on.