code 0421... o2 sensor, or cat? on 2006 Mitsubishi Eclipse

We have changed 3 of the 4 o2 sensors on this car, it still throws the code whenever it feels like it. Got it scanned and they said the bank 2 sensor 2 wasn't following the rest of them. Is bank 1 the side by the firewall? and could my whole problem be sensor 1 on bank 1?

Asked by for the 2006 Mitsubishi Eclipse
stop guessing and throwing parts at it. you need a cat, not any of the sensors.