cel
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Secondary O2 sensors, tuned, still needed?
On my last car, even though the 2nd cat codes were turned 'off' I needed the o2 sensor installed and plugged in to maintain proper fuel trims, not only did it need to be there but it could not be in a 'extended o2 tricker' housing. Had to be in the exhaust flow directly. I would get +12%-+18%...