Hello all. I’ve been lurking for a bit while attempting to fix my P0420 code on my 2008 with 162k miles and decided it’s time for a post. The CEL came on about a year ago (always on, not intermittent), shortly after which my cat got stolen off my car. I thought, great timing! Now I’ll get this taken care of and insurance will cover the replacement. A new cat was put on by a local muffler shop, but the CEL came back on right away. So they put another cat on. Same thing. Then I went traveling for 7 months and came back recently, CEL still on. So I brought it back to the shop and they thought it was the O2 sensors, which were both original and apparently reading incorrect voltages. They replaced both, and the light still came back on after each replacement. They seem pretty lost and not sure what to do next. Is it possible the light was originally thrown for a bad o2 sensor, and then they replaced the cat… and then in my 6 months of driving with the new cat and the (possibly) bad o2 sensor that would have ruined the new cat? And now that the o2 sensors have been replaced they’re fine but the light is now on for the damaged cat and that needs to be replaced again? Any suggestions where to look next? Thanks.