Somethings up with my O2 sensor

[kristen_1819]

Turbo underboost is a shadow code for the O2 sensor (from my mechanic) but that was just done in January- brand new. Any ideas what this could be/ why it’s happening. He asked me about my CAT which has never been replaced. The last time this CEL came on was almost 3 weeks ago, I cleared it and it came back on mid driving today. What do we think?