Check Engine Code P0420
 

hey Guys,


My Check Engine light came on last Thursday, i took it Autozone for them to pull the Codes. It came back with the code P0420. Had to do something with the Cat Convertor being below threshold. I have a 98 Accord EX with 93K miles 4 cyl. On Saturday I change the oxygen sensor that is connected to the converter and reset the ECU. The car is runnig fine and the check engine light did not go on again. Its been 3 days already. Just want to let people know that was my problem and I was able to resolve. Surprise that the 02 sensors ont hese models failed so soon.

RE: Check Engine Code P0420
 

Hopefully, the new O2 sensor fixed your problem, however this code takes some time to set as the ECU monitors performance for a long period to determine converter efficiency. So it may be early to declare victory. Any exhaust system changes or air intake modifications can affect P0420. Honda cats are very durable. I've never had a bad cat w/ over 500K miles on Accords, plus another 200K+ on similar Acuras (family cars not all my driving).

I had this code on my 99 Subaru Forester. It would come on and I would reset. It would stay off for periods of weeks to several months, but always return. I finally installed an aftermarket, Eastern direct-fit replacement converter which so far (4-5 months) has fixed the problem.

good luck

RE: Check Engine Code P0420
 

Way to bust his bubble Texashttp://www.6thgenaccord.com/forums/i...ies/madrun.gif. JK. I know I would be mad if I replaced my o2 sensors and my CEL came back on with the same code after a month or to. Well, if your CEL comes back on, at least you know what to do now.

RE: Check Engine Code P0420
 

A 98 accord with a p1420 code: 99.9% chance it needs a cat.

RE: Check Engine Code P0420
 

make that 100% .. every single p-0420 codes that i have seen, the only way to have taken care of it was to replace the cat and in a few cases the o2 sensor as well

RE: Check Engine Code P0420
 

Most people here say that the Cat. Convertor are suppose to last longer than 92,000 miles. Its hard to believe that the Cat. is done and needs to be replaced. Just hope the O2 sensor change did the trick. Been driving for a week already and 300 miles so far. If it was the Cat. then the CEL would have came on already. Crossingmy fingers.

RE: Check Engine Code P0420
 

An Update....Nearly 700 miles and almost two weeks after replacing the O2 sensors at the cat converter, The CEL did not go on. Chiovnidca said it was the cat but i guess not. I'm lucky that its not. That would be a pain

RE: Check Engine Code P0420
 

Don't get too cocky just yet..........

RE: Check Engine Code P0420
 

If you have access to a scanner that will graph some of your key outputs, check the rear o2 sensor voltage vs. time plot. Is is smooth at 45-60 mph w/ fully warm engine or rough w/ constant peaks/valleys? If the later, the P0420 may come back. If it's smooth, I think your problem is fixed.

good luck

RE: Check Engine Code P0420
 

The Car is running fine and smooth. I don't notice any jerks or chokes from the car. I think I'm getting a little better gas milege as well. Hope this is it.