Gremlin SES Light 01Path

[pstapler]

This is somewhat of a follow-up to a previous post I made but I am getting a new OBD code so I figured I would make a new post. I recently replaced the Cam Position Sensor and Crank Position Sensor on the driver side and both downstream O2 sensors, all of which I was originally getting OBD codes for. I cleared the codes, unhooked the battery for a couple hours, reconnected the battery, drove the truck for 15 miles and the SES light comes back on. Now I am getting code P0420 (Two-way Catalyst System Bank 2).
Is this a result of the ECM relearning the proper mixtures after replacing the downstream O2 Sensors and will clear itself up after a while? Or is it another real problem?
TIA

[stemo76]

O2 sensors aren't going to stop you in your tracks. They probably need replaced but you can just rest the codes again and see if they come back. If they do you need to resolve.