P0420/P0430 with OEM cat on ‘07 JK

Mike Baker

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Hi, new to the forum and new to JKs - I’ve had 4 other Jeeps over the years but nothing newer than a TJ.

I’ve read the other threads about P0420/P0430 but my situation seems different. The previous owner installed Rugged Ridge headers but didn’t change the cats - so as far as either of us know they’re OEM (they were replaced in 2018 at the same time as the O2 sensors, and have less than 20,000 miles on them).

So while high flows cats can cause P0420/P0430, could just installing headers with OEM cats cause the same codes to come up? Would O2 footers downstream from the cats fix the problem (when P0420 is the upstream sensor)? And finally am I likely to do any damage with this setup? I’d rather not clog up the cats if I can avoid it.

Thanks!
 

BLACKJKU

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I have long tube headers with high flow cats and had to use the O2 foolers to clear the codes. I also had to put new O2's in when I installed the headers and put in NTK sensors. That was 3 years ago and never had any CELs for that since.
 
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Mike Baker

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I have long tube headers with high flow cats and had to use the O2 foolers to clear the codes. I also had to put new O2's in when I installed the headers and put in NTK sensors. That was 3 years ago and never had any CELs for that since.
Awesome - thanks. Do you think for the headers alone it is a question of new sensors, adding foolers, or both? And unfortunately the Amazon link in the other thread is broken - which foolers are you using?
 

BLACKJKU

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Awesome - thanks. Do you think for the headers alone it is a question of new sensors, adding foolers, or both? And unfortunately the Amazon link in the other thread is broken - which foolers are you using?

You only need the down stream foolers anyway that's the only ones I needed. Are those codes the down stream CEL's?

The last time I checked the foolers I bought weren't available anymore, i'll have to look them up and see if they might be now.

The ones I bought are not available anymore, but I had to have 90's for clearance and they came with 3 discs. If I remember right I used the middle sized hole and it worked.

 
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Mike Baker

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You only need the down stream foolers anyway that's the only ones I needed. Are those codes the down stream CEL's?

The last time I checked the foolers I bought weren't available anymore, i'll have to look them up and see if they might be now.
Those codes could theoretically be either - P0420 is Bank 1 and P0430 is Bank 2, so it doesn’t specify which sensor it is. That said, the downstream sensors are checking for variation from the upstream sensors, so logically putting foolers on the downstream ones should eliminate the problem. And given that the upstream ones are supposed to control the air-fuel mixture, I’d rather not mess with them.
 
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BLACKJKU

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I just found some just like the ones I bought, only I got mine on Amazon and they are no longer available there.