I always thought a faulty O2 sensor code would specifically say "O2 Sensor" and the specific side/bank when read on an OBD2 Scanner.
The fact that your reader specifies "Catalytic Converter" may mean it's actually that.
I'll let someone else with a little more know-how than me chime in.....
Truck was sold today [5/19]. I got an offer I couldn't turn down. I had no more need for a pickup so I cut it loose. About to purchase a '14 Jeep SRT8 this week.