Hello everybody, I recently purchased a used automatic 2000 Hyundai Accent with 106,xxx miles on it. I purchased from a dealership (big regret now) when I bought the car the check engine light came on, being smart I took it to a near shop to run the codes where it came up as P0422, catalytic converter failure. Well I immediately called the dealership I was buying it from and they said they would fix it because before the final papers where signed over it had to pass emissions, and with this code, it would not.
So I took it to the dealership, dropped it off and went to school, I wish I could have stayed but I am a college student and couldn't afford to miss any classes. I got a call back saying it had passed through emissions and my car was ready to be picked up.
A few hours later I went and signed the rest of the papers officially putting the car in my name. I drove it for about an hour when BAM light comes on again code p0422.
I called the dealership and told them the light came back on and tough luck. (big surprise, POS dealership)
So my question is, since obviously the catalytic converter wasn't replaced how would they make this light go off to pass emission. I read that unplugging the MAF can turn the light off for a little while but it didn't fix the problem only make it unreadable.
Also is this for sure 100% the catalytic converter I also read that replacing the o2 sensors might fix this problem?
Any info is greatly appreciated
Thanks
Chad
(I apologize if this has been covered I have searched and just haven't found the answer I'm looking for)

What your code really means is the front O2 sensor and the back O2 sensor have reading which are too similar, which indicates a problem of some sort. It's possible that you have an O2 sensor that is faulty, but generally you wouldn't be able to tell unless you did some diagnostics on the sensor or replaced it. It could also mean the CAT is bad, since that would also produce similar O2 sensor readings.

If it was my car, I'd probably replace the downstream O2 sensor first since they go bad anyway after 100K miles, clear the code, and see what happens. If that's not it, then it's likely the CAT is bad. You won't know if the CAT is bad without taking it off and looking inside.

Some other possiblilities are:

Leaking exhaust system, i.e. flex pipe.
Coolant temperature sensor giving false readings, causing too much fuel to be burned.
Loose timing belt giving false timing.

Thank you for the reply, I will definitely be replacing the O2 sensor first since it is way cheaper then replacing the cat.

Well, downstream o2 sensor was replaced, then I reset the codes, drove 60miles, and the light came back on.

Here is a picture of the downstream 02 sensor, looks pretty burnt up. I think the next step is to replace the front one maybe its just as bad.
Im trying to eliminate all the causes before resulting to a bad catalytic converter.
sorry for the quality taken with my phone.
(IMG:http://i62.photobucket.com/albums/h93/crad008/1112091649.jpg)


This post has been edited by Crad008: Nov 13 2009, 06:28 PM