Just threw the above code. Changed out the O2 sensors and the code reappeared after 20 miles or so. Checked with Honda and a new OEM Cat is $900.00. Since the car is a 2000 with 250K miles not interested in spending that much on a part. Anyone have any suggestions on a good aftermarket cat? I'm looking at the Evan Fischer Cat, it's around $120.00. Appreciate any suggestions, thanks.

 

With a car that old just find a bolt on and call it a day. They have a good magnaflow one eBay for $150. What brand sensor did you use. It still may be the sensor. Honda's need to have the OEM. I had the same issue and never needed a new cat.

 

Thanks for the response. I installed Denso's, which I believe are OEM. I also used a laser temp gun to check front and rear cat temp. The rear was lower than the front, that shows that there is a blockage. I heard about cleaners that you put into your gas tank, but there are mixed reviews, so I didn't try it. The car also began to hesitate on the highway, after I cleared the code, that's when the P0420 code returned. My daughter has an Honda Element and she had the same code. The O2 sensors cleared the light, so I know that sometimes it works, but I can't complain after a quarter of a million miles on the old cat.

 

I bought a stainless steel Magnaflow cat for when my 99 Accord was throwing the P0420 code. I got it thru e-bay for 150 shipped. I even re-used my old O2 sensor. Code is gone. Magnaflow offers a 5 year warranty on their cats. I also went with their stainless steel cat back exhaust system. It has a lifetime warranty. I live in the salt belt, so I wanted SS so I wouldn't have to get under the car again for a long time.

 

Changed out the OEM Cat with an aftermarket brand. Took the OEM cat to a recycling plant and the first thing they asked me when I got out of my car is if I was going to scrap the car. Anyhow, they gave me $70.00 for my old Cat. Since I only paid $100. for the aftermarket one, it's almost a wash. I'll post back up after I get some miles on the car, but so far all is good in Accord land. Thanks for the input!