Strange temperature and fan issue

[Brother Bluto]

My truck did something very strange today. Drove it last night on a 2 hour round trip - Zero issues.

On the way to work this morning, noticed the coolant fan was full on. Noticeably loud in the cabin. At the same time I noticed that the temperature had not climbed above 160 - the lower level of the gauge. No CEL or any other warnings. Pulled in to check coolant. After a 10 minute drive, the coolant reservoir was warm, not hot, and level fine. I did have heat into the cabin. Finished my commute and the fan ran for a while after shutting down.

Same thing on the way home, until, all of the sudden, the fan stopped and the coolant gauge climbed to normal. Not gradually climbed, but the gauge shot up.

My thought is it that I have a bad temperature sensor, but not sure why that would trigger the fan to go full out.

Any ideas?

 

[Jeff_]

Do you have an OBD scanner? If so, plug it in and see if any codes are being thrown.
Likely throwing a code that it isn’t reading the temp, so the ecm cranks the fans on thinking it might be overheating.

 

[R3N3R]

My 2015 yukon denali did the same thing today but temp Guage was not giving any readings at all. Gonna get the truck scanned soon.

 

[Terry2015Tahoe]

My 2015 Tahoe did the same thing. I replaced coolant temperature sensor. Problem fixed! Posted here:

Good luck!