Thecheck engine line (CEL) came on and we took it to Autozone to get a free code reading. It was P0420, which turned out to be a very popular code for all Honda Accords. We have a 1999 Honda Accord LX with 140K miles. We called several local Honda dealership and received an estimate of $1K to replace the catalytic converter (CV). This has to be done in order for our 1999 Honda Accord LX to pass the State of Texas annual inspection. We took our vehicle to ahighly recommended muffler shop and they replaced an after market CV, with the total cost less than $300. It has been a year now and the CEL has not come on and needless to say, our vehicle passed the annual inspection.

I have done quite a bit of research on this P0420 code and there are a lot of good recommendations. I have tried all of the home-remedies and none seems to work for me (ie. add fuel additive chemical into the gas tank, rev up the engine at a lower gear on the
highway, erase the computer code, buy super unleaded gas, replace OS2 sensor, get a tune-up, replace spark plugs wires,
replace with Honda manufactured CV, and etc....)

This has proven to be an easiest method of fixing P0420.

Good Luck !

 

$40 test pipe with o2 cheater..........no where near "legal" but it wont set off a code. Destroys the environment, but who really care about that anyways.

 

Just some info for others, the local recycler here pays $60 for Honda converters.
He claims they are the best; to recycle of course LOL

So if you have the chance to grab your old one it might help defray the costs of replacement.