I had something similar (but not nearly catastrophic) with my truck when my DEF pump when out after the 3 year 36,000 but before the 5 year 100,000 mile diesel warranty was up. The Chevy dealer near that could get me in (not the selling dealer) said it wasn't part of power train so it wasn't covered. Fast forward a couple weeks and I am chatting with another Duramax owner and come to find out he had the same issue and his was covered as part of the power train warranty! I went to our local GMC dealerwhere I actually get my truck serviced for an oil change and asked them about it and he confirmed it should have been covered. Long story short the second dealer did some legwork for me and a few weeks later I had a check in the mail.
It's amazing they don't know what's covered and not.
Dan
