I know there is a guy on here that will try to refute this, and I would love his input as well. What I want to know is if there is anyone on here that has, for certain, had a P0420 code on a jeep liberty, (bank 1 to be specific) and replaced an 02 sensor, and have it fixed the problem and clear the code? I see countless search results online that say it could be a downstream 02 sensor, but I can't find a good and easy way to test the 02 sensor. They all say pull it out and spend more time with all these weird tests than it is worth to avoid buying a new one. Thanks in advance and all advice is greatly appreciated! Second question, if I do need to replace my catalytic converter, what would be a good option under 250 dollars that can bolt right on without welding or cutting or doing any custom work?