2005 Nissan Pathfinder O2Sensor Bank 1 Sensor 1 Question

[HT_Moving]

My scanner recently read P0420.
My ACTON Sensor indicates Catalytic Efficiency Threshold Below.

To verify the operations of my O2 Senor operation (while in park) I increaded my RPM to 2000 and I noticed O2S11(V) had displayed minimal change (0.298 to 0.305). However, the remaining senor increased to approximately (0.500 to 0.600).
While driving O2S11 displayed minimal change (0.298 to 0.305) while the remaining sensor increased to 0.700.

I changed Bank 1 Sensor 1 because it appeared to be the defective sensor. Unfortunately, after driving 50 miles and monitoring the sensor, the problem has not been resolved and the check engine light is back on.

Has anyone experienced this problem.
If so, how did you fix the problem?

Thanks