just got this code yesterday after taking care of p0449 and p0128 do I need to replace second cat or do I need a new o2 sensor?
thanks brother much appreciatedMy suggestion would be to replace both O2 sensors and see if that fixes the problem. They are both way overdue anyway. ACDelco sensors are probably priced best at rockauto.com or Amazon. The #1, upstream, sensor is ACDelco 213-3207, GM PN 12592592. The #2 (downstream) sensor is ACDelco 213-3139, GM PN 12585999.
Aftermarket sensors are also available at RockAuto and Amazon or at most local parts stores.