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

One question I have on this if someone is informed enough to answer. Does the 420/421 code actually effect fuel mapping, or inversely can it be caused by too rich/lean fuel mixture? If it's just an issue with the performance of the CC, then while it's not great, there's little in the way of damage. If it's changing the fuel mapping as a result of the code/situation I'm concerned. If an off fuel mixture can cause it then I'm much more concerned as the issue could be completely outside of the exhaust system (while unlikely as it's correlated closely with changing exhaust parts I still want to worry sufficiently if I should). Thanks in advance for any intel.

 

I don't think the CEL changes anything. Once I found out it was just a cat problem, I ignore it. The car performs perfectly otherwise.

The funny question to me is, why no CEL when the pre-cats are deteriorated, but then I get one with new headers with only 3K miles on them? It's total BS.

 

When I replaced my headers I changed the 02 sensors just because I had a pair of brand new ones, I kept the old ones that work perfectly, I can sell them to you for cheap if the mini cats don’t fix the CEL, but I am pretty sure they will, just do the 12 hours+ battery kill, and if it doesn’t resolve it do it again.
I did SEVERAL battery kill switches until it worked, the overnight worked but maybe (just maybe) the ECU needs several resets to adapt. So maybe the overnight was just a coincidence because for me killing the battery for 30 mins vs 12 hrs SHOULD NOT make any difference but it did. So try several resets before you throw the towel.


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I have Agency Power headers and a Kline exhaust. After installing just the headers, I got a P2193 CEL which was fixed by replacing the relevant o2 sensor. This set up produced no errors whatsoever after that.

I then put on 200 cell sports cats in place of the stock cats and started getting P2192/93 errors. I tried to remedy this by installing some right angle mini cats (no name brand from Amazon) and the P2192/93 codes went away but were replaced by P420/30 errors indicating cat below efficiency. These codes appear within a short drive after clearing them.

If I remove my mini cats, the error codes will switch back to P2192/93. These codes may appear within 2 weeks of them being cleared.

I have a feeling I have an exhaust system leak somewhere and may try replacing the header gaskets.

 

The EU cars have no pre-CATS and basically the same car. What is different in the ECU tune of a EU car that only has the main CAT and the US car with pre-CATS that causes the code when you remove the pre-CAT?

Someone earlier posted their CS exhaust came with different PN O2 sensors. Did we ever get that PN?

Is the EU cat a different part than the US CAT?

Also, would flashing your ECU to a EU spec. get rid of the errors?

 

My experience.
My 360 was euro. (no precats) installed de-cat pipes, got cat codes straight away. Didn't like the sound so fitted high flow sports cats. Sounded better and no more CEL's.
My 430 is euro, switched to challenge headers with no precats. Got cat codes straight away. Fitted 45deg O2 extenders, pointed back towards engine, no more CEL's. 3 years now.
Anything more than headers and sports cats and you will not get lucky with extenders/minicats. It is hit and miss, some don't get lucky at all. From what I've read it seems more difficult with US spec cars. Different tunes for different countries.

 

In case some of you didnt see the engine ECU reset procedures after replacing the car battery or turning the master switch off that someone posted here - here it is.

I think I copied this from a post by Taz. Thanks Taz!
Please see attached.

Note: I frequently turn my battery master switch off whenever Im working on my car so I printed a hardcopy of this and placed it in my glove compartment for easy retrieval.

Dan

 

Thanks for sharing Steve!

And I agree!

Dan

 

07 F430 here. Fabspeed headers wrapped in blankets. Everything else stock Got P0430 code right off the bat. Put O2 extenders on. Code didn't happen as often but still did. Put minicats on. No issues so far after several start and stops.

 

Please list the parts, as I'm not familiar with the details. Brand of headers, cats, O2 extender, minicats, and exhaust can. This sounds like the path I want to go.

 

Hi, I have a 2002 360 Modena. Fabspeed headers, Hyperflow cats, Ferrari CS Exhaust, ( I installed the complete CS Exhaust kit including the ECU's programmed for my car and exhaust by FOA, CD O2 Censors).

CEL's were driving me crazy. They would come and go in a random fashion. My ODBII scanner indicated the CEL was initiated at a speed of 50-60MPH (2000-3000rpm). Sometimes I could go several weeks without a CEL and at other times CEL's would appear on an initial drive after an ECU reset.

I tried different extenders without ever resolving the CEL problem. In further discussion with Fabspeed they suggested I try their Mini cats (about $100). I installed the Fabspeed Mini Cats and have not received any CEL's since.

I installed and Steve Bisel's Bypass controller after the installation of the Fabspeed Mini Cats without any issues.

Hope that helps.

 

Thanks for the updates Steve.

I hope you sort this out soon so you can start to enjoy driving her again CEL free.

Dan


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Did you install the mini cats??
Try the overnight reset, it is a long shot but it worked for me


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Okay, Fabspeed headers. Does Fabspeed also make the Hyperflow cats? I have the CS exhaust. The ECU's for the CS exhaust I have not heard about before, so I'll check into that. CD O2 sensors? Are those OEM or aftermarket? And the eventual key to the solution was the Fabspeed Mini Cats. I am also unfamiliar with the Steve Bisel Bypass Controller; what does that do?

 

Allows you to force the exhaust valves open for more noise - normally open according to RPM on the 360.

 

Thanks, I like the automatic valves. They are perfect for me.

 

The CS exhaust kit came with 2 new ECU's that have to be programmed by the dealer. Likewise the O2 sensors. They also came with the exhaust kit. Hyperflow cats are not made by Fabspeed. They were on the car when I purchased it.

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O2 extenders came with the Fabspeed headers. The blankets are from Capristo. The minicats are also from Fabspeed (90 degree fitting). The primary cats and exhaust can are OEM.

 

Thanks, I think I have everything I want figured out now. Fabspeed headers w/02 extender, Fabspeed Minicats @ 90 degrees. I will try this with stock cats and my CS exhaust first, then maybe add sport cats to the setup.

 

I'm not using O2 extenders with my Fabspeed mini cats.

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Nice to know. I don't want to fiddle around, so I'm going to get the whole setup.