Code P0420 in NY - Can I buy a used OEM Cat to replace it?

You could have this Cat shipped to a friend in a different state: EPA Catalytic Converter for 2004 2005 2006 2007 2008 2009 Toyota Prius 1.5L L4 | eBay It might not pass the visual inspection in California, but maybe in New York they're less strict if they have to remove a cat shield to do the visual inspection of it?

The noise is probably coming from the flange gasket failing between exhaust manifold and Cat pipe because the cat is clogged and creating back pressure. You could try a cat soak recipe and try to get it cleaned out and working again?

As for a used one, maybe you could get lucky and pull an OEM one off an old Prius, but buying a used OEM online will probably not go well, because they're super valuable. As in look at the precious metal prices for 2 grams of Rhodium, 2 grams of Palladium and also platinum and you'll pay more than that for a used OEM cat that might be clogged or soon will be clogged.

 

I'm not sure what the standards are in New York anymore If you have a missions but parts aren't missing critical In other words you're allowed to replace crap that isn't working with parts of equal quality made by whoever if you can get away with that then you're in good shape these cheap cats can get you through a year maybe two maybe a tad longer You got to shop carefully and buy the brick type converter not the fine wire or whatever it's called they just burn up immediately or pretty quickly

 

Maybe we could get the metal stamp of the Toyota logo they use to identify OEM cats?

 

I'm sure a tool making place Forge shop whatever could whip one up directly All they need is a picture.