The check engine code says bad cat.
Any chance Chevy warranty covers this? They used to cover emissions gear for 100,000 miles!?

 

I believe they still do. Unless I'm mistaken, that's a federal law. I wouldn't be at all surprised that it did fail. Trailblazer's for example are well know to have a high rate of cat failures anywhere from 75k to 120k.

If the dealer covers it, see if you can get them to change your front O2 sensor also.

 

GM hasn't covered emissions items for 100K since 1991. The cat warranty is 8/80K. Call your dealer and see if he will goodwill it to you.