2007 G35 Journey, 212,xxx miles. I recently had the P420 code come up so I ordered a new cat plus all 4 O2 sensors. I'm still getting the P420 code. I checked the O2 sensor voltages using a BlueDriver code reader and it shows the bank 1 sensor voltage is lower than sensor 2. Sensor 1 voltage is in the .45v range while sensor 2 is in the .78v range. Bank 2 sensors are behaving normally with sensor 1 at .8v and sensor 2 around .4v. Anyone seen the strange behavior I'm seeing on bank 1?

Tom