Check engine light on and code P0430

If your scan tool is capable, look at mode 6 data. This will be test result data for several drive cycles, which will tell the whole story of what the module is seeing. You just might have a bank 1 that is faulty also, but has not set a code yet. P0420,430 never lies! They sold you a vehicle with bad cats after they cleared the codes is what it sounds like. but to be sure this guide can confirm the issue

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please run down this guide and report back.

Just to jump in, when you say the o2 sensor are fluctuating and the other side appears to be operating, what at they fluctuating from?

I agree that the most likely cause is the cat but you could have a faulty upstream/downstream sensor making the PCM think the converter is faulty.

I am attaching below the testing for this code which will find a faulty sensor. However, I would just start with switching the o2 sensors side to side and see if the code changes to the other bank. If it does not then you have a cat issue or one of the less likely causes listed in the testing. If it does then you have a sensor issue. If you want to at that point, you can move one of the sensors back and try to narrow it down to one sensor. However, I would just replace them all at that point.

Let us know thanks

That is good. However, I see you have bank 1 sensor 2, this is the downstream (after converter), and bank 2 sensor 1 (before the converter). We need to compare Bank 1 sensor 1 to Bank 2 sensor 1. Then each bank sensor 2 to each other.

You should see both these upstream sensors reading about the same and then bank 2 downstream sensor will be off from bank 1. This will indicate that the converter is not reducing the emissions.

The way this works is the upstream measures the air/fuel coming out of the motor. The downstream measures the air/fuel after the converter and it needs to see the oxygen content higher then prior in order for it to see that the converter is reducing the emissions.

As you can see the bank 1 sensor 2 is reading under.1 volts the whole time. This is good as.1 volts is high oxygen content. The closer you get to 1 volt the less oxygen there is in the exhaust which means there would be more fuel.

So again if the downstream sensor is reading high oxygen content then it assumes the converter is not doing its job. However, this could be due to a faulty sensor if it is reading incorrectly. If the upstream is reading too low or the downstream is reading too high then it will think the converter is not doing its job.

So just get both upstream voltages and downstreams and we can go from there. Thanks

I am sorry but I could not make out the numbers. I think the upstream numbers looked okay, but I couldn't see the downstream at all.

Let's just swap the o2 sensors and see if the code moves to the other side.