P0421 / P0431 Trouble Codes (Catalytic Converter) ... anyone have good fix?

Check the amount of clearance you have. The mini cats ate large and you may not be able to fit extenders and mini cats. The 90 degree mini cats just had enough clearance .

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The mini cats are 02 extenders with mini cats inside of them. How can you not be using extenders?


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Here is what I'm using. No need for a spacer.

http://www.fabspeed.com/universal-o2-spacer-with-catalytic-converter/



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And that is a spacer with an added mini cat inside. I don’t think anyone is using a combo of spacers with mini cats along with regular spacers. And yes that is what I use too and it works.



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The block unit (90 or 45 degree) that comes with the fabspeed mini cats are the spacers. the block also are fitted with cat material. I ran fabspeed headers, fabspeed test pipes, OEM exhaust & Kline. Both trigged a CEL. Also note of caution, when running the mini cats, it did not hold on fabspeed test. The weight of the mini cats with the combo of heat and vibrations, the mini cats cracked off the test pipes. This has happened to me and few others here.

I'll post some pic if I can find them.

 

The 45/90 degree block is not a spacer is just to make the installation easier (it has a bit of cat honeycomb inside but I don’t think it makes a difference for DTC codes), otherwise the larger mini cat would be at a perpendicular angle to the cat, and therefore not fitting and/or cracking the catalytic Converter or test pipe (yes I remember this has happened to others), I installed mine with 90degrees so they are sitting parallel to the cat and not touching anything else.



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Mine was 45 degree during failure but one other had them at 90 degree, also with failure....so it can happen with 90's as well. You have to use the blocks or take those off and use some sort of 90 degree spacer. There is not much space in there.

....back on topic...the best way get ride of the CEL is to code it out. I'm having my ECU's done by Mase but chose not to code it out. I'll just clear them when it pops up.

 

Of course it can happen with either block but I think that the larger mini cat attached perpendicularly to the cat or test pipe (no block) increases these chances because it is actually heavy and creates more leverage.


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lol This is way more complicated than it should be.

 

Haha it is not, I got rid of codes with the mini cats AND an overnight reset (several short resets didn’t work)
I have Fabspeed headers, hyper flow cats with Fabspeed mini cat 02 extenders and Tubi exhaust, it sounds EPIC.


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Lol, yes, I've been keeping score. Some with your setup still get CEL's. But I think I'll try the Fabspeed headers and Fabspeed mini cats/O2 extenders with my stock cats and CS exhaust first. The long reset does seem like a key.

 

For people running testpipes like me ....I don't think you can avoid the CEL. I'm selling my mini cats if anyone is interested.

Good Luck!

 

This is the reason I went with Agency Power headers, stock Cats and Kline Exhaust. = Zero issues.

I want to upgrade my car, address the known weak issues, then just drive it and enjoy it.

Last thing I want is check engine light or spending so much time dealing with fault codes and dealing with other upgrade issues / headaches.

 

You are the first to bring up those headers (I bookmarked them already). How do they address the absence of the pre cats? Relocate the O2 sensors?

 

Dan, you were lucky because some cars do get codes by changing the headers and some don’t. I had codes when I replaced the headers with Fabspeed. At the end the mini cats worked and they still do after I installed the hyper flow cats.
Just some cars are not sensitive than others, just like some cars get rid of the codes with the mini cats (or regular spacers) and some don’t.

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I have a cat delete and these Fabspeed O2 sensors / minicats with 90-degree bend:

https://www.fabspeed.com/universal-o2-spacer-with-catalytic-converter/

I've never found any 0421 codes but I have this one darn anxious code "0139 o2 Sensor Slow Response (Bank 1 Sensor 2)". Usually its "pending fault" so it wont lit the CEL. But maybe two times during the last summer & 5k miles I drove her it was "current fault" state and the CEL was lit.

My stupid question is that is it related to the cat delete & minicats or is it related to the car own o2 sensors? The car is Euro spec.

 

Hi Fernando,

I don't consider it luck as I did my research and due diligence searching, reading so many threads, reaching out to other owners and I concluded that Agency Power headers plus stock catalytic converters does not throw any fault codes.

Then when Kline exhaust came out other Kline owners informed me that adding Kline exhaust to AP headers does not throw fault codes as long as stock cats are used.

So I went with that set up and I confirm no CEL.

Dan

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And another car with the same setup could throw codes, it is always a coin toss. So “luck”is always a factor with aftermarket products.


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Ok I'll play.

Would you be so kind and point me to a thread on a members F430 with agency power headers, stock cats and Kline exhaust that has issues with check engine light?

I thought I did a thorough research but I may have missed some.


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Don’t become defensive Dan
I am so glad you did all your research but Kline (or any kind of) exhaust has nothing to do with codes mentioned in this thread. The codes happen in SOME cars when you mess around with the parts where the 02 sensors are connected to (manifolds/headers or catalytic converters) and I can assure you several F430 have thrown codes after swapping to AP headers.



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The brand of header wont make a difference. The difference is the missing pre-cats. Mine is stock apart from challenge headers. Threw cat codes straight away. O2 extenders fixed it.

 

Exactly!!


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The thing I don't get is the euro cars don't have pre cats and they don't get codes.

 

Different tune maybe??


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I recently went with Fabspeed headers, Topspeed High Flow Cats, with current Tubi exhaust along with Big Daddy O2 extenders and minicats. No CEL light yet and have 300 miles on the setup on my 2004 360 Spider.