I had my first check engine light a day ago. I am on the road so I took it to a dealer in Las Vegas too have it looked at. Turned out to be a problem in the wiring to the oxygen sensor. Repairs were made and two other reflashes were needed as well, all on warranty. It appears that there are notifications for all three of these issues. I'm not sure what changes were made but I noticed a change in the sound of the engine and a change in driveability, both for the better. I will be towing again next week so I'll see if there is any difference there. So far I really like this truck!!!