P0420
Catalyst System efficiency below threshold

I bought the car with this check engine light and its been hell i changed the full exsaust an aftermarket one and replace it and the person i bought from said he put new sensors in and that wasnt the problem. What do i do whats the problem? i have seeing this check engine light and want to see it gone.

 

BUMP

 

Catalytic Converter may need to be replaced.

 

Should I get an OEM cat is that the problem you think?

 

You can't go wrong with OEM.

 

I have the same issue. You're going to pay at least a stack + if you go brand new oem. And it'll be a headache looking for a used one with little mileage. I'm going with a magnaflow direct fit 49 state just to get rid of the error + bolting on the heat shield to cover it up to pass smog.
Good luck to you

 

yeah thats what i would do if i had that code, and im sure it will pass smog with the mangnaflow as well. the o2 sensors are working because they are reading the efficiency of the chemical reaction. If an o2 sensor was bad it would more they likely be the downstream and have a totally different code.

 

So the aftermarket for the Si's aren't good? Will that catalytic work on the aftermarket exhaust system I have ? I don't need to replace whole thing right ?

 

How much are you spending on all that?

 

i was just sayn "if" i had that code thats what i would do. Buy the mangnaflow cat. better air flow and still legal i believe.

 

http://forums.clubrsx.com/showthread...=842256&page=2


I have heard aftermarket catalytic converters can be he'll.
Also aftermarket o2 sensors can be problematic

You need an OEM cat at a minimum, then if the code still appears, replace the rear o2 sensor, then if needed the front A/F o2 sensor.

Note the last post in my attached link is an OEM cat for sale.

 

or if you don't care about emissions, it is time for you to get a "RACE HEADER!!!"

 

Yea, you're going to have to replace the cat. If you don't care about replacing it and the check engine light bugs you, get a defouler.