How to cure Cel/Mil from removing cat with Non-Fouler

You can try to put a screen or some type of heat resistant block inside the nonfouler down where the small whole is so that you are not allowing as much emissions in at that point since you don't have the pre carb anymore. You may also have to go ahead and replace that O2 sensor as well because that could be bad if it continually triggers the cel.
 
Sorry brain fart on that one! Inactivity... so it may be too far out of the exhaust stream already?? Or the sensor is going bad and just not corking properly. You can get a univeral bosch or denso to just splice in for about $70 at the auto parts which is much cheaper than the dealer.


Did you relocate it to after the cat?
 
I'm in the same boat as some of the rest of you. I installed the non-fouler along with the header because I had seen this issue even before I bought it. Does the O2 sensor HAVE to get a reading? Is it possible that we could completely block off the hole with some JB weld or something? I cleare the P0421 code and a couple days later the CEL came back. Haven't verified, but I'm assuming it's the same code.
 
Does the O2 sensor HAVE to get a reading? Is it possible that we could completely block off the hole with some JB weld or something?

Someone correct me if I am mistaken, but your O2 sensor needs to get a reading. By taking the non-fouler approach to avoiding the MIL/CEL, you are merely changing the physical resistance being registered by the O2 sensor by supplying it a lighter amount of emissions. If it doesn't get a reading at all, your system should interpret this as a malfunctioning O2 sensor, hence a CEL is thrown.

The purpose of the alternate route to avoid the MIL/CEL is to hardwire a resistor into your O2 sensors wiring to bypass the reading all together. So by going this route, you're essentially locking your O2 sensor into a single permanent reading that all is well with your emissions.

So, if you want to block off your O2 sensor all together, you will have to do the hard-wire resistor fix for the CEL.

http://www.mazdas247.com/forum/showthread.php?t=52498
 
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Sorry, stupid moment. Thanks for reitterating that.

P.S. Cleared the code again and we'll see if the ECU has learned to accept my slightly irregular reading, or if a hardwire is in my future.
 
There is a possibility that the O2 sensor itself is not functioning properly... Which could cause the CEL. Also check to make sure all 4 of the wires to the sensor are in good shape.
 
Is it possible to install this non fouler kit on original factory setup exhaust ?? I have P0421 code after had multiple misfires(P0300 code). Fixed the multiple misfire problem by changing coils but still have problem with P0421 code and I was wondering if this non fouler trick work with factory exhaust.
 
Is it possible to install this non fouler kit on original factory setup exhaust ?? I have P0421 code after had multiple misfires(P0300 code). Fixed the multiple misfire problem by changing coils but still have problem with P0421 code and I was wondering if this non fouler trick work with factory exhaust.

You may actually have a damaged/malfunctioning cat though. If you ran long enough with a spark misfire, that means you were dumping raw fuel into the cat, which makes the catalyst metals inside heat up and eventually melt. Yes this would take care of the light, but it will not FIX your problem. Just FYI.
 
I did this trick with my friends NISMO header on his Sentra and it's worked well for the last 400 miles.

I was thinking about buying a bunch on spark plug non-foulers and drilling them out with my drill press and selling them basically for cost + shipping to members. Would anyone be interested? I understand a lot of members either don't own the tools or have a work shop to do this.

Post if you're interested or PM me. I'm located in Cleveland OH and can ship via FedEx Ground or Express the next business day. I work in a small shop and we have plenty of small boxes and ship out orders through FedEx daily.
 
i did this after i installed my obx header and it worked great.. i checked the codes and none were there after i installed it... after about 300 miles of driving the check engine light came back on and its bogging again like before...why did it come back on and how can i fix it?
 
I'm one of the guys that has the code come back regularly. Turned out to be an exhaust leak between the sensors. Make sure all of your bolts are tight and run your hand along the exhaust while revving the motor to see if you can feel anything. Which code are you getting specifically? Mine is P0421.
 
Hey guys, thanks for this thread I just read the entire thing. My moms car is getting a Cel
P0431 Warm-up catalyst system (LH) efficiency below threshold ON 2 Catalyst
So I bought a new 02 sensor just in case but I think I may try this 1st because I got a 3 wire universal 02 sensor and it looks like i'll need the 4 wire..

My question is I know the car has 4 02 sensors. which one is bad? I take it LH means left hand side, is that standing in front of the car or in the drivers seat left hand? Also it as mentioned to do this to the 02 sensors after the precat converters? does anyone have any pictures or diagrams? Do you do this mod on the 3 wire front or 4 wire rear or dies it matter? Sorry I am all confused. I have been looking at mazda forums all day and I still dont know. Thanks
 
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I think i have answered some of my own questions by reading this whole post again.
install the non-fouler on the second 02 censor? ( closest to the ground)
I just want to make sure I am installing it on the correct side which looks to be after catalyst on left side of engine, which i think looking at it from the front of the car is the righ hand side.
 
Yes, the Left side of the car is AS YOU SIT. The front of the engine is where the pullies are. Front wheel drive engines are almost always mounted sideways under the hood. LH on our engines would be closest to the front bumper. Make sure you pay attention to which way the engine is facing. The protege only has 2 oxygen sensors. Don't know what sensor you're looking at to get a 3 wire, mine both have 4.

What does your mom drive? How many miles?
 
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