I wanted to drop a note of thanks to this forum for the help I was able to find regarding this particular check engine code - P0420.

althougth Ive been to this forum many times in the past, this will be my first post. I had previously owned a 2002 Honda Accord, 4 dr. 4cyl. But, my goal was to get a 2003 Accord 2 dr. manual. Last month, it finally happened, and I brought home my new accord. However, two days later, my check engine light came on! while I was very discouraged, I did the research, and turns out now, all is well.

I initially went to Advanced Auto, and had them run the tool to check the code (this after the dealer was going to charge $100). I got the P0420 error, and after researching on this forum, found that the error was related to the cat. converter. After more research, I found that this device is under warranty by a federal emission regulation for 8 years or 80,000 miles. I called the dealer the next day, got an appointment and took it in. They had the car for several hours and got a call at the end of the day - replaced with no charge. Great experience with the dealer here in Mishawaka, IN, and thanks to this forum for helping find the answers I needed.

 

Thanks for posting. It's nice to know when something helped.