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Discussion Starter · #1 ·
I had a stock exhaust, no codes etc. Installed MBRP offroad catback with single core high flow cats and immediately got the 0420/0430 code. Is this just a common code since the high flow cats obv arent as efficient as stock? Or is this actually a problem? The cats appear to be hot since its flaking the high temp paint of them that the exhaust shop sprayed on it.
 

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Do you have access to a laser temperature gauge? What does the shop have to say? Is this a registered daily driver or an unregistered off road only vehicle?

Did you ask the manufacturer about it? They have a toll free number - try calling them to see what feed back they might have.
 

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Discussion Starter · #3 ·
I had n exhaust shop do the work, they told me not to touch the cats but im stubborn n went for it. He laser temped the cats and i thnk they were a little on the hotter side but it had been sittn for a few mins. At this point i cant get bak there to find out right now. I cant see how the cats would b that much hotter since theyr in the same location?
 

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I have yet to see paint not flake off of a header after install, even though it is "high temp," I would assume a cat would do the same.

I had this same issue when I replaced my oem header and exhaust on my sentra. It is a common problem when going to an aftermarket setup.

Easiest, cheapest fix is to get a spark plug anti-fouler and screw it into the o2 bung, then screw the o2 into it.

What this does is pull the downstream o2 sensor out of the exhaust stream and fool the ecu into thinking the the cat is working like it should.

The high flow doesn't usually work as efficiently as the ecu would like, and therefore will throw the code you mentioned.
 

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Discussion Starter · #5 ·
From past experience w other vehicles id get lights just from the increased flow/lack of filtration etc...just woinderin if this is the same or if im onto n issue
 

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Discussion Starter · #6 ·
Willms81 ok thank u for the advice, i assumed that was the case. Iv done major motor builds etc before on mustangs etc n never worried bout little lights etc but this is my dd n im not experienced enuff w jk's yet so just wanna play it safe
 

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I have yet to see paint not flake off of a header after install, even though it is "high temp," I would assume a cat would do the same.

I had this same issue when I replaced my oem header and exhaust on my sentra. It is a common problem when going to an aftermarket setup.

Easiest, cheapest fix is to get a spark plug anti-fouler and screw it into the o2 bung, then screw the o2 into it.

What this does is pull the downstream o2 sensor out of the exhaust stream and fool the ecu into thinking the the cat is working like it should.

The high flow doesn't usually work as efficiently as the ecu would like, and therefore will throw the code you mentioned.
Sounds like you might have had a Spec V eh? I had an 06 and took off all cats and ran a header back exhaust. That thing screamed lol but it was fun. I to ran the o2 spacer on the downstream o2 and the light never came on, sounds like this would work for the OP as well
 

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Sounds like you might have had a Spec V eh? I had an 06 and took off all cats and ran a header back exhaust. That thing screamed lol but it was fun. I to ran the o2 spacer on the downstream o2 and the light never came on, sounds like this would work for the OP as well
lol...yes I do. Mine is an 02.
 

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Just an FYI, you MAY have to drill out the center anti-fouler in order for the o2 to seat properly. I had to do it on mine.
 

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Discussion Starter · #12 ·
Awesome thx fellas Im gonna give this a shot!
 
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