well it has about 135700 miles on the engine, i dont think its clogged because im still getting good acceleration and i havnt had any performance drops. Im pretty sure the individual o2 sensors have separate codes than the p0420 for the catalytic converter. i live in Illinois so there are no emission regulations or inspections, just laws that you have to have a cat on your car. what do you mean you have to have o2 sensors to run? Thank you both for your quick replys!