PO135 Code

I get this code on my 04 Avalanche with 100K miles. I have a general understanding of what this is, and how to fix it. I'm wondering what would happen if I just ignore it and don't fix it at all. Could that result in further damage? Affect performance? Be dangerous? etc. I may not have this truck long and am trying to decide what to do. Thanks.

You don't want to wait too long it may cause the Catalytic converter to overheat and go bad.

If you are near NJ, I can help replace it.  Did it on my 05 with 120K miles.  Was a bit of a PITA, but cost was under $50.  I have the tool to replace it as well.

Thanks for the info and offer. I'm in Texas so will have to work locally.

O2 sensor?

Will cause Cat damage and really low fuel mileage.