1999 a6 p0432 p0411

I'm getting both of these codes now.
The right catalytic converter was replaced recently. And actually I may have been getting these codes even before I replaced the catalytic
converter...but I'm not sure.
Would a bad right oxygen sensor explain both of these codes (as well as the bad catalytic converter)? I've heard that a vacuum leak might explain them as well....but I haven't been able to detect one (using the carb and choke cleaner).
Any help would be greatly appreciated.
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