My new to me 2010 Jeep Wrangler (3.8L) has 120k miles. Both P0420 and P0430 came on, indicating that the cats on both banks are not functioning.

I first checked that the O2 sensors had readings using a bluetooth OBD2 reader. They show readings and seem to be functioning.

Then I noticed that each side of the engine has 1 broken bolt on the exhaust manifold. I read online that an exhaust leak could cause issues so I paid an exhaust shop to extract those bolts, but they were only able to extract 1 of them. I cleared the ECU codes and drove around for a while and both P0420 and P0430 came back. Since one side has all the bolts, that tells me a leak isn’t causing the issue.

I bought O2 spacers online to see if that makes the codes go away. After installing the spacers on the rear O2 sensors and driving around till the Catalyst test on the ECU completed, the codes did not come back. Does that rule out O2 sensors having issues?

Does that confirm that cats on both sides of the engine went bad? What are the chances of both sides failing like that at the same time? ugh… going to be an expensive repair if its the cats.

  • waynep712222@alien.topBEnglish
    1·
    1 year ago

    I would love to see wider sample of the wave forms. At idle and 2500 rpm. So you have at least 10 cycles on the images.

    The lower two links show that the cats are not reducing emissions. Was that with cold cats. They have to be hot and run at 2500 for a minute or two to get a good accurate sample.

    Those lower two look like you dont have any cats at all

    Try again.