I want to reflash my car with hp tuners with a different tune but if the engine goes in the next 4 years, will it be covered. Do they have any way of seeing if it was reflashed?

 

yes and no

 

If you reflash it prior to taking it in then they won't know.

I'd recommend buying a used pcm on ebay reflashing it to the factory tune and changing the vin to your vin then just keeping it as a backup...would cost about 100 bucks.