PO420 code Honda Accord 1998 - HELP!

[jnjharris]

My car is throwing the PO420 code even though the emissions are within passing limits. To me this would indicate that the catalytic converter is functioning properly, however my car will not pass the smog check until the code is cleared. What can I do to see if my catalytic converter needs to be replaced or determine if something else is causing the problem?

I have heard that this is a common problem for 1998 Honda Accords and that another code will be thrown even after the cat is replaced indicating yet another erroneous problem - Can anyone else validate this problem as common?

Any advice is appreciated.

[Igovert500]

P0420 67 Catalyst System Efficiency below Threshold.

Some stuff to read:

http://www.obd-codes.com/trouble_cod...old-bank-1.php

http://www.automotiveforums.com/vbul...79&postcount=4

http://www.automotiveforums.com/vbul...17&postcount=2

http://www.automotiveforums.com/vbul...ighlight=P0420

Apparently, it is a pretty common problems on the 98 and 99s. If the emissions testing is within passing limits I would tend to agree with you.

First, I'd unplug the negative battery terminal for a minute, let hte ECU reset, then hook it back up and drive it around. See if it comes back on. Next, I'd check for an exhaust leak. In the cold night air, they are pretty easy to see. Turn the car on, and look under near the cat and see if you can see any. If no, taking it to a muffler/exhaust shop and asking them to check the temperature of it and see if they think it's failing, might be the next good idea.
Being that you aren't getting any other codes, I wouldn't think it's an o2 sensor.

Bottom line, if it is indeed your cat, I wouldn't order one from Honda. $500-1,000 is ridiculous. You can look on ebay or otehr sites mentioned in one of those links and pick up a replacement or a high flow cat for under $150.

[jnjharris]

Thank you for all of the information - I really appreciate it!