Emissions code PO430 - Bank 2 Catalytic Converter Efficiency

[jpbrooks81]

I would love to know what came of this as well. I have a 2011 xc90. Engine light came on. OBD2 code was P0420. Mechanic quoted me 5K to replace catalytic converter. I said no way! Talked to another mechanic. He gave me BG44K fuel additive. Drove about 200+ miles. I followed that up with Cataclean. After filling up, engine light came on 2 days later. Same code, P0420. Ive read so many of these posts, and it seems like people go down a rabbit hole of replacing parts and still unable to fix the problem. Has anyone been able to find a fix for this? All of these message boards just drop off without any solutions that actually work.

[bumperplates]

Hi,

How did you go in the end after running thinner through the tank?

Did you need to replace the bank 2 cat in the end? Is that difficult to do without pulling the whole engine apart?

Thanks

[bumperplates]

Would you recommend the Lacquer method to see if it can overcome a P0430 code in the V8?

Hmmm. I'll throw some thoughts at this and you can make of them what you will.
First thing, more of an FYI is that the threshold for cat efficiency is very low, something like 5% I think. Ie if your cat is at 94% efficiency, you can throw a code for it.

So did you end up replacing both of the sensors and the cat on bank 1 to "fix" it?

Since the banks share a MAF so I think we can rule that out for now. Same with a vacuum leak, its a possibility but I think right now that's further down the line.
Has the pre cat O2 on the offending bank been replaced? If not that might be my next port of call, the sensor might just be out of spec enough to cause the mixture on that bank to be out therefore causing the post cat O2 sensor as a result of the actual gasses passing by it, or the cat getting slowly coked up.

My recommendation would be to replace the pre-cat O2 sensor on bank 2 and attempt to clean the cats by adding laquer thinner to your fuel tank..

One last thought is that a leak in the exhaust, from the manifold down to and including the cat could also throw an efficiency code.