I was assuming it was covered by warranty since the op said the warranty was still good. It's been years ago, but the last esp I got(given to me due to multiple ac failures by 30k miles) covered anything mechanical in nature. Depending on his warranty it might still be covered.

 

I have a '19 F-250 6.7 with 3,000 miles. I was driving on a residential street and all of a sudden the battery light came on, air conditioning turned off and power steering went out. I pulled over and popped the hood, to my greatest surprise the serpentine belt came off. Any ideas why this would happen? Power surge? Bad tension pulley? I'm quite dumbfounded being it only has 3K miles.

 

Power surge? No.

Usually a belt fails when one of the pulleys fails. However, usually the belt will break when an idler pulley seizes. If your belt is not broken, you probably have a failed belt tensioner. You should inspect all items that may impact this, just to be safe.

— Dave

 

Djosbun the belt isn't broken. It's odd to think failing parts when there's only 3,000 miles on the truck. It's under warranty, so I hope the folks looking at it will inspect all items. Thanks for the reply, it's greatly appreciated!

 

I learned a long time ago that just because a part is new doesn't mean it's any good.