After doing more research on the P0430 cause, and after all the trouble shooting done that ruled out many other causes to what could be the cause of the B2 CAT code, the current probable culprit is highly likely to be a leaking B2 fuel injector, lets see if my diagnoses is correct, I will have to pull the fuel tube out and pressure test it with the injectors still connected.
Will update if I was right or wrong on this one, if wrong the next step is to do some multimeter wire Voltage checks. If right maybe I caught it in time to where the CAT has not lost its efficiency and it is still good (unlikely).
I did find a tidbit of info that might give meaning to the AF Sensor Voltage readings (B1 0.3V and B2 0.6V) we have been getting on our after market scan tools? This is from the PF MX book DTC P0420/430 ck list:
Overall Function Check UBS00K8W
Use this procedure to check the overall function of the three way catalyst (manifold). During this check, a 1st
trip DTC might not be confirmed.
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Open engine hood.
6. Set voltmeter probe between ECM terminals 74 [HO2S2 (bank
1) signal], 55 [HO2S2 (bank 2) signal] and ground.
7. Keep engine speed at 2,500 rpm constant under no load.
8. Make sure that the voltage does not vary for more than 5 seconds.
If the voltage fluctuation cycle takes less than 5 seconds, go to
EC-316, "Diagnostic Procedure" .
1 cycle: 0.6 - 1.0 → 0 - 0.3 → 0.6 - 1.0
The cycle above starts at 0.6V to 1V then cycles to 0V to 0.3V then back to 0.6V to 1V. Is it possible B1 AF Sensor has its base set to the second cycle 0.3V rate while B2 is set to 0.6V cycle the same as with the O2 Sensors above? It would make sense that the Banks would be on different cycles from each other while the scan tool reads the live data, if you think about it the scan tool reads some of the two Bank's data as if there are two separate engines.
If anyone who reads this has a 05 or 06 Pathfinder and a scan tool what is your baseline Air Fuel Sensor Voltage readings on Bank 1 and Bank 2?
We have ours at B1 around 0.3V and B2 around 0.6V.