136 error code lean HO2 sensor?

Okay, so, recently I changed out the catalytic converter on the left side of my vehicle because it was burnt to a crisp. It affected the O2 sensor, so after being replaced it kept giving me the same engine code. I know the right Cat was good, so I only replaced the left. But does that mean I should replace both O2 sensors on each side? I also disconnected the battery to hard reset ECM, but there was no luck.