I recently had a new header (Megan Racing 4-1), high flow cat (Magnaflow universal), and B-pipe (T1R) installed on my EM1 and pretty quickly got the infamous CEL PO420 code, which indicated a problem with the cat. So I did the easy thing and replaced the secondary O2 sensor with a direct fit Bosch and cleared the CEL. A few days later and I am getting the same CEL. Any ideas on this? The magnaflow cat should be good enough to not throw codes like that right? If it is an issue that cannot be fixed, is there a 'fix' for that code?

 

if its a high flow it will most likely make you throw that code . you should have gotten a direct replacement from magnaflow mine works fine no codes

 

I am under the impression that there is no difference between high-flow and direct-fit other that the OEM style flanges welded on to the direct-fit.

 

I read somewhere that there can be an issue with too much air flow past the second O2 sensor. It prevents it from operating correctly. So, all you need to do is put a little extension pipe in place which places the O2 sensor further away from the secondary catalyst. You can look around at your local exhaust shops but you are likely to find one on the internet easier.

There is one you can buy from here:
http://www.procivic.com/pages-produc...032/index.html

It will solve the CEL issue but it may not allow you to pass emissions....I don't know for sure.

 

Cat is Magnaflow part 54055 like this:

http://store.summitracing.com/partde...part=MPE-54055

The extender is a good idea, thanks shailoche.

 

thats what why I said direct fit because u dont have to do anything except pop it on or weld it right in place. If U get a high flow the O2 senses too much of the bad **** since its flowing more and more freely . so u would either have to do what he said further the o2 or get one of those 02 plug things that stops the O2 from sensing anything.(if I remember correctly

 

There is some difference in flow. With OBDII the ECU is really sensitive compared to OBDI or ODB0. As such you have to make your O2 sensor isolated from the main exhaust flow. The magnaflow cats are less restrictive than stock but not as free flowing as some others. As such they tend to not throw CEL codes as often. However, this is fairly common with high flow CATs so they devised that little pipe bung that I posted in my other post.

The most important thing is that by altering the catalytic converter you may have created a situation where you will not be able to pass emissions. If you are in California the laws are so strict that any modification of a catalytic converter on a vehicle with ODBII is against the law unless the CAT is visibly damaged or the auto has more than 50,000 miles on the car. So, make sure you read up on that law. Otherwise the use of the pipe bung usually solves the issue.

 

O2 plug, i think i remember reading about that somewhere around this forum, time to do some searching again, thanks for the advice IP RACING.

 

Forget to mention/clarify; I am in a dirty-emission friendly state, so no worry about passing emissions, thanks again shailoche

 

There are also O2 sensor eliminators which you wire in place of the O2 sensor. Those can be had in a lot of places. But once you alter that wiring you kind of go into no-mans-land since there is no telling what your ECU will do.

This CEL is a problem that can be solved but for the sake of being legally correct and not getting kicked off of the forum....be careful and note that although I offer the advice I don't condone any particular course of action.

 

Looks like the extender is the way to go, I have enough room that I shouldn't need the angled adapter, so I'll get a much cheaper straight-adapter like this:

http://www.inlinefour.com/blcelelad.html ; although likely buy off ebay as it is cheaper there.

Thanks for the prompt replies

 

My only concern for that is that if you spent the money on a good cat, exhaust, header, and installation you shouldn't skimp on the one part that will allow your engine to run without throwing a code. I am in no way affiliated with any of these businesses I just like to make certain all my hardware is the best and that it has been designed to eliminate whatever problem I am having. I know that the extender at www.procivic.com works as I have had experience with it. As for the others at www.inlinefour.com or Ebay I do not know of their quality. Just my .02

 

I hear ya. I am a bit of a stickler when it comes to quality hardware also. In this case, I am not seeing anything too complicated when it comes to a O2 sensor mount extender. The Weapon-R part that you linked to does indeed look like a quality piece. Although I am not seeing anything wrong with the BLOX branded part I found either. The only advantage to the Weapon-R part that I see is that it is angled, but I have enough room under there that I won't need an angled piece. We'll see how it goes. Thanks again.