I have a 01 trans am ws6. I have been getting P0420 code and I replaced the 02 sensor after cat. Still getting code. I noticed the 02 voltage on bank1 sensor 2 drops from 0.9 to 0.065 volts and fluctuates back and forth. Bank 2 sensor 2 stays around 0.8 volts. I also installed a simulator today to see if it would help and the voltage is still fluctuating from 0.9 to 0.065 volts. I assume the voltage dropping so low is setting the code. What should I look at next? Thanks