An exhaust leak can also cause an erratic O2 lean condition.
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An exhaust leak can also cause an erratic O2 lean condition.
Personally i would go a little richer while in boost, like what farmtruc said, 12.2 is a little too lean but not overally bad. And do a boost leak test ( introduce shop air into the intake system) Your tune can be just by a small little vaccum leak and would have to re-tune your fuel side again. What system are you using to tune with?