2009 Ford Taurus X O2 Sensor

I have P0420/P0430 engine code popping up. Trying to determine if its O2 sensor related or bad Catalytic Converters. I have OBD II scan tool that reads live data, and when observing the O2 sensors on both bank 1 and bank 2, both sensor 1 and sensor 2 of both banks rapidly change anywhere from .035-.900 volts. It does this in all RPM ranges. Does this indicate the sensors are working correctly and my Cat’s are in need of changing? And/or is there another test I can or should perform on the O2 sensors to confirm they are working properly?