I am having the same issue with my 2016 Yukon slt. All fans began running (temp gauge at zero, fans ran when vehicle was turned off and continued to run when restarted) at almost 100,000 miles. I replaced the coolent temp sensor and it seemed to have fixed the problem for a couple months. The problem began again so I bought another temp sensor from the dealership. The problem seemed to be fixed for another month or so. Problem started again so I replaced the connector plug as I thought it could have a fitment issue. The problem went away for a couple weeks and it’s back. I am basically disconnecting the battery and resetting at this point and am unsure what to do now.