Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Federal emissions warranty is 8 years, 80k miles, so if the catalyst is the problem then it would be covered. Any manufacterer is going to want to have confirmation that you have had your maintenances done on schedule, as there are some things that could cause the catalyst to fail prematurely- worn spark plugs, failed coil, overfilled oil level, etc.
But just judging from the smell, it sounds like the catalyst has failed and is no longer converting your exhaust gases properly- too much sulfur being emitted from the tailpipe.