O2 Sensor

[Necction]

Well my computer is throwin an SES code , and it says Bank 2 O2 sensor Insufficient switching. So First of all which side is bank 2 driver or passanger ? And how do I go about fixing this problem, like do I just change the O2 Sensor and if so where is it ?

Thanks

EDIT: I have true duals , one cat is directly after driver header and the passanger one is in regular spot.

The o2 problem only came recently.

[Long Drive]

I've slipped in a tank of regular on occasion, and each time it throws an O2 code. When I go back to high octane, the SES goes off! Dealer not sure why, but so far I have not had to replace the sensor.

[2001NBMZ28]

Bank 1 is driver side, Bank 2 is passenger side - the code will tell you if it's sensor 1 (precat) or sensor 2 (postcat).