[wait4me6920]

What you need to do is go through the terminology of your warranty very carefully to determine exactly what is and what is not covered, & if covered, to what extent. Powertrain is a very general descriptor & your particular warranty may or may not cover the crankshaft position sensor, timing belt, etc...

I kinda wonder if the guy that installed the sensor screwed up, leading to the backfire, shredded belt & possible further damage...

Good luck...