07 2wd 5-speedauto
The only wild guess I could think of, maybe the ECM runs a knock sensor test after filling the tank to test the knock point of the fuel. Of course this only a guess, and there is nothing in the service manual description and operation. I do know that GM used to run a knock sensor check on every start up.Thanks for the tip. I'm certainly willing to try it, if I can figure out how to get to the darn thing. I don't see how in the world the tank filling could be related but it's happened so many times I actually replaced my gas cap, hoping that might be the common thread. No such luck. Thanks again for the tip on the lubricant.
good luck with the lube. Post back in a few months if it stayed fixed.