That's a great question. I have wondered myself if it was possible to replace your catalytic converter and O2 Sensors with something more sensibly priced then dealer parts.

I have seen Cats from Bosal and Walker in the $150 price range and if they really don't work... how can they be sold. There are cheaper sources online than Autozone. I read a post that talks about the lifetime of those parts being about 2 years vs 15 for Honda parts from other posts. There is a costly material in them that is the catalyst and maybe the brands I mentioned just use less?? not sure. I would like to see a response from anyone who successfully put in a similar brand for the Honda Accord and had a track record of success.

Also I saw postings that people had replaced O2 sensors with Bosch and engine codes came back very quickly. Those are $70 each vs the Honda which is $250 ish I think. Do those not work either? I thought Bosh was a good brand. Maybe those owners replaced the wrong parts?

I have the code for the cat and have been living with the check engine light. Performance and fuel economy are still good and somehow I got past inspection earlier this year with the light temporarily off.