I had a little fenderbender that scratched headlight cover (R/H) few weeks ago.
so I replaced it with one I got from eBay. (great condition)

Now I found condensation in that headlight -
* Can dealer refuse warranty just because it's not the original one, or one bought brand new from them ?
* You think the dealer will discover that it was not the original one
and refuse to cover the replacement under warranty ?