How to get rid of P0420 using spark plug anti fouler

Technical info on the Pontiac Vibe and Toyota Matrix including do-it-yourself info
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yyamad1
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How to get rid of P0420 using spark plug anti fouler

Post by yyamad1 »

So this has been discussed, we know it is insufficient cat converter. I tried the resistor mod in blue wire with the right ohm, all it did was once i cleared the CEL it stays off for the duration of the drive. After restart it pops back up. I have a scan gauge so I was clearing it during long trips... but got to be a pain. So I went out and bought the spark plug anti fouler from AZ for 4 bux. had to drill out the one with 1/2 inch bit. The tip of the O2 sensor is less than 1/2 inch but its a tight fit. screw two in and put it back in. My CEL has not come back ever since. I have removed the resistor as it was not a permanent fix in my car. The theory behind this mod is that first spark plug anitfouler has such a small hole that little exhaust air passes thru the sensor. In turn fooling the ECU into thinking the CAT is working as it should. I have read that people can remove the cat all together and with this mod, the ECU will continue to think the Cat is working just fine. here are the pics.
yyamad1
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Re: How to get rid of P0420 using spark plug anti fouler (yyamad1)

Post by yyamad1 »

this is how it looks drilled out.

Attached files
yyamad1
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Re: How to get rid of P0420 using spark plug anti fouler (yyamad1)

Post by yyamad1 »

this is installed. so far 1 week no more CEL!

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Bedlam
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Post by Bedlam »

great suggestion yyamad1. I use this myself on both of my cars after learning of it on my dodge forum a few years back. We utilize this mod with 1 change. between the 2 anti-fowlers we put a bit of steel wool in there to help pool the exhaust gases even further. I have dual 3" mid pipes on my SRT with hi flow cats and in order to fool the computer consistently we needed the extra layer to trap the gases more and give the sensors an appropriate reading so we can pass a ODBII based inspection.I tried that resistor mod on my latest Vibe and it did nothing so this past October I did the same mod to get rid of that stupid light. Frankly, my 7-8 year old cat isn't worth replacing and my mileage is still over 30 so the 5$ and 30 minutes required to do this mod is well worth it.
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yyamad1
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Re: (Bedlam)

Post by yyamad1 »

thanks, i hope it helps some one out. I think in our cars we dont need the steel wool you mentioned, because today, I gutted my cats and still no CEL lol
Bedlam
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Re: (yyamad1)

Post by Bedlam »

Quote, originally posted by yyamad1 »thanks, i hope it helps some one out. I think in our cars we dont need the steel wool you mentioned, because today, I gutted my cats and still no CEL lol nice. Based on the size of the pipe and the fact that it is a 1.8L engine, i don't imagine it has the velocity issues the steel wool was meant to abate. These little motors just chug along and i am glad to see yours is still doing the trick.
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bassplayaz06
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Re: How to get rid of P0420 using spark plug anti fouler (yyamad1)

Post by bassplayaz06 »

my code came back yesterday, so i'm gonna do this today.
2003 Vibe GT, 1.8L, 6 speed Manual Lava Red 2 tone18" sport edition rimsCosmo CAIMy Garage http://forums.genvibe.com/zerothread?id=42483
bassplayaz06
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Re: How to get rid of P0420 using spark plug anti fouler (bassplayaz06)

Post by bassplayaz06 »

code came back the day after. advance auto guy suggested having mid-grade fuel in the last fill up being a cause.
2003 Vibe GT, 1.8L, 6 speed Manual Lava Red 2 tone18" sport edition rimsCosmo CAIMy Garage http://forums.genvibe.com/zerothread?id=42483
yyamad1
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Re: How to get rid of P0420 using spark plug anti fouler (bassplayaz06)

Post by yyamad1 »

Bassplayaz, you drilled one out and left one normal? and screwed the normal in exhaust then drilled out, then o2 sensor? did u clear the ECU? and how old is that O2 sensor?I wonder about the age of the o2 sensor because before doing these mods, I did install a new O2 sensor, both pre and post. I have read in so many forums that people have cut off their cats and still no P0420 with this mod, so Im pretty sure its a sure thing in our cars.. perhaps you could try the steel wool trick like another guy posted in this thread? I understand his theory/logic... makes sense i mean.I highly doubt the gas grade is going to make a difference.
BlueCrush
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Re: How to get rid of P0420 using spark plug anti fouler (bassplayaz06)

Post by BlueCrush »

Quote, originally posted by bassplayaz06 »code came back the day after. advance auto guy suggested having mid-grade fuel in the last fill up being a cause.Mid-grade? You should be using Premium in the GT!!
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bassplayaz06
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Re: How to get rid of P0420 using spark plug anti fouler (yyamad1)

Post by bassplayaz06 »

i always fill up with premium. dad decided to use mid grade to save money. i checked it today, the o2 sensors are kinda old.
2003 Vibe GT, 1.8L, 6 speed Manual Lava Red 2 tone18" sport edition rimsCosmo CAIMy Garage http://forums.genvibe.com/zerothread?id=42483
bassplayaz06
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Re: How to get rid of P0420 using spark plug anti fouler (bassplayaz06)

Post by bassplayaz06 »

also you changing both the O2 sensors would have canceled the CEL.
2003 Vibe GT, 1.8L, 6 speed Manual Lava Red 2 tone18" sport edition rimsCosmo CAIMy Garage http://forums.genvibe.com/zerothread?id=42483
joshuaeb09
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Re: How to get rid of P0420 using spark plug anti fouler (bassplayaz06)

Post by joshuaeb09 »

I gave up on the anti foulers with my 09. Tried stacking 'em, steel wool, etc. I ended up dropping the cash on an 02 Sim. It really did the trick no more p0420 from no precat and my 02 sensor looks completely normal
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TheRollingThunder
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Re: How to get rid of P0420 using spark plug anti fouler (yyamad1)

Post by TheRollingThunder »

Fantastic thread, used it on my vibe. the principle is there, and when i went to my local advanced auto parts the parts guru said he used to use this same trick back in his day, so i was sold. Hopefully my code stays off, drove 65 miles so far, fingers are crossed Odometer read 193.425
MetalFiend
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Re: How to get rid of P0420 using spark plug anti fouler

Post by MetalFiend »

I am planning on swapping out the OEM header for a 4-1 ratio. I have been reading a lot about this mod and hope it works on my 09 2.4L FWD. I will post once I'm done.
FrankenVibe
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Re: How to get rid of P0420 using spark plug anti fouler

Post by FrankenVibe »

Got this code and when I went to change out the O2 sensor, this mod had already been done by the previous owner lol. The anti foulers rusted out and the O2 sensor looked beat. Broke off the O2 sensor with part of the anti fouler, had to drill the rest out. Looking for new anti foulers now, is there a certain size I should be looking for?
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joatmon
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Re: How to get rid of P0420 using spark plug anti fouler

Post by joatmon »

FrankenVibe wrote: Fri Mar 11, 2022 5:46 pm is there a certain size I should be looking for?
in viewtopic.php?t=47790 Mark posted a link to the Dorman 42009 anti foulers from autozone that he used, and then nato posted a bunch of pictures about the task, so check out that thread

those antifoulers are a hard metal, a bit of a chore to drill out the one
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CraftsmanQuad19
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Re: How to get rid of P0420 using spark plug anti fouler

Post by CraftsmanQuad19 »

They sell actual o2 defoulers that bolt right on specifically for this purpose. No drilling or “spark plug defoulers” necessary. My car hasn’t had a cat for over a year now and never had a p0420. Just google search an o2 defouler and it’ll pop up
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FrankenVibe
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Re: How to get rid of P0420 using spark plug anti fouler

Post by FrankenVibe »

joatmon wrote: Sat Mar 12, 2022 7:10 am
FrankenVibe wrote: Fri Mar 11, 2022 5:46 pm is there a certain size I should be looking for?
in viewtopic.php?t=47790 Mark posted a link to the Dorman 42009 anti foulers from autozone that he used, and then nato posted a bunch of pictures about the task, so check out that thread

those antifoulers are a hard metal, a bit of a chore to drill out the one
Thanks for the link to the other thread. No kidding on how hard they are, took me forever to drill out the old one while the exhaust was still in the car!
FrankenVibe
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Re: How to get rid of P0420 using spark plug anti fouler

Post by FrankenVibe »

CraftsmanQuad19 wrote: Sun Mar 13, 2022 8:40 pm They sell actual o2 defoulers that bolt right on specifically for this purpose. No drilling or “spark plug defoulers” necessary. My car hasn’t had a cat for over a year now and never had a p0420. Just google search an o2 defouler and it’ll pop up
Thanks for this, I don’t have a drill press, so it would be very difficult for me to drill out the anti fouler. My research is bringing up M18x1.5mm thread pitch as the standard for most vehicles, so I’ve decided on specifically one of these 2 defoulers:

http://www.bigdaddiesgarage.com/straight-cel-fix.html - comes out to $15 shipped

https://bloxracing.com/products/02-diag ... 2466487468 - comes out to $21 shipped

At I correct in thinking either would work?

Edit: I went with the Big Daddies Garage version, I’ll advise results once I get it installed and emissions checked here in NY.
cigvibe
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Re: How to get rid of P0420 using spark plug anti fouler

Post by cigvibe »

This is the style that I used. I have an extra one for the next person that needs it.
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FrankenVibe
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Re: How to get rid of P0420 using spark plug anti fouler

Post by FrankenVibe »

Update: Installed no problem, passed emissions and the code hasn’t come back. Good to go.
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