01 S-type 4.0 v-8 local repair shop says engine fault code was left bank O2 sensor , i purchased new 02 sensor before catylitac converter installed it on the driver / left side, took back to reset engine code. It woked fine for about 15 minutes, Then engine light came back on. Question is left bank mean driver side ? Is it possible that it is the down side of the catylitac converter? thx for your help!!