Not sure if its my oxygen sensor or bad or clogged catalytic converter or both. I had a misfire a month ago. Obviously runs alittle rough on start. Once warm it runs fine. Any thoughts on pics I posted. Thanks
I posted a few pics but I'm not sure. Pretty sure the upstream and down stream oxygen sensors are original. The vehicle has 235k. Actually have never had to replace a down stream oxygen sensor on any toyota I've ever owned.
Usually the sensors have their own codes. P0420 is most often a bad cat, typically caused by oil burning. You can check the vehicle's cat efficiency monitor which runs almost every drive cycle. Example from Car Scanner app on my v. This is a particularly good reading. Most captures are closer to the minimum. Note the egr flow test above. That is a good result and will repeat closely each capture. That is with two cleanings in 325k miles and one updated egr valve. The following is a more detailed method to manually check the cat by analyzing the sensors Finally if I get to the point where cat replacement is necessary (in a non Carb state) Walker cat detail
