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  1. #1
    Veteran Member Four Rings Seerlah's Avatar
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    DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

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    When people place a HFC or TP onto their exhaust system, a CEL for Catalyctic Converter Effeciency Below Threshold usually pops up. Not in all cases, but in many cases it does. You recieve this code because with the addition of a tp/hfc the exhaust flow increases and the 02 sensor feels that there is something wrong with your stock catalyctic converyer. This mod basically fools the secondary 02 sensor by placing the 02 sensor further back, where the 02 sensor is no longer in direct path of the exhaust flow. This mod does not only remove the CEL, but also lets you pass readiness for the catalyctic converter when inspection time comes around. [Please note, that this has been known to not work in some cases for the AWM. But I have an AWM with HFC, and this mod works for me.]


    Total time: 30min-1 hour

    Difficulty on scale from 1-5, with 5 being the most difficult: 1

    Tools needed:
    Help! 42002 Spark Plug Non-Foulers (2 in box)
    7/8" Socket/Open End Wrench
    Power Drill
    1/2" Metal Drill Bit
    High Temp Anti-Seize
    Vice Grip (not necessary)
    PB Blaster (to remove 02 sensor from bung)


    1. The first thing you want to do is spray your secondary 02 sensor with PB Blaster and let it sit for an hour, to be able to take it off the bung. That is if it is burnt onto the 02 sensor bung, which more than likely it is.

    2. Spark plug non-fouler before pic


    3. Now, you will need to drill the ID (inner diameter) of it to 1/2". I used a power drill with a 1/2" metal drill bit. I also don't have a vice clamp, so I used a different technique. Of course it would be better to place the non-fouler in a clamp and drill it from there. But for those whom don't have one, what I did was hold the non-fouler in place with a 7/8" socket wrench and drilled with it planted on a flat surface (it may be best to use a wood prop underneath it). Then clean off any metal shavings left over from drilling.






    3. The spark plug non-fouler after drilling


    4. Next thing, is to remove the 02 sensor (you may want to unclip the conector before doing this, as to not kink/twist the wires) using the 7/8" wrench or an 02 sensor removal tool. In the picture, I purchased a new 02 sensor because my old one was done for. Place High Temp Antiseize on the threads of the 02 sensor and thread your 02 sensor onto the non-fouler (be sure not to touch the head of the 02 sensor nor get any antiseize on it) and toque them together nicely (I used an adjustable wrench and the 7/8" wrench to tighten them together).




    5. Now you are ready to place the 02 sensor back onto the bung. Place high-temp anti seize onto the threads of the non-fouler, simply place the 02 sensor and non-fouler back onto the secondary 02 sensor bung, torque it down with the 7/8" wrench and you are done (if you disconnected the 02 sensor, simply plug back in).


    In some cases, 2 non-foulers may be needed. But I only needed one. Also, I removed my stock air box for more room to work, but it is not necessary.

    *Disclaimer: Neither Audizine, any of it's members, nor myself will be held liable for any mishaps which may incur.
    Last edited by Seerlah; 06-19-2010 at 05:08 PM.
    I hate it when my car acts like a little bitch, treating me like the bitch

  2. #2
    Veteran Member Three Rings
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    2001 A4 1.8TQM, 2009 GSX-R 1000
    Location
    Seattle

    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    1/2" may not be quite big enough to fit the sensor, mine needed to be drilled a bit larger diameter and I've read other people on this forum also having to drill the hole slightly larger than 1/2" but it's a good starting place.

  3. #3
    Veteran Member Four Rings Seerlah's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    I had mine drilled at 1/2" for over a year and a half now. Passed inspection and all with no issues. I just made this DIY because I replaced my 02 sensor, and figured "why not?". I needed to replace that thing with a new one anyways.
    I hate it when my car acts like a little bitch, treating me like the bitch

  4. #4
    Senior Member Two Rings slideitsidewayz's Avatar
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    1998 Audi A4 1.8tqm gt2871r
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    should this work on an AEB engine? if so...im doing this tomorrow! haha....good write up!

  5. #5
    Veteran Member Four Rings Seerlah's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    This mod should work with just about any vehicle. I am not sure how advanced monitoring systems get (as in sensitivity), but B6 guys can do this 2.8 guys, B5 S4 guys, etc. If you are doing this mod because you have a turbo-back exhaust (no catalyctic converter), you wil need to place 2 non-foulers onto the secondary 02 sensor bung.

    This mod is essentialy the same thing as purchasing this: Clicky Click
    Last edited by Seerlah; 08-10-2009 at 01:16 PM. Reason: spell check
    I hate it when my car acts like a little bitch, treating me like the bitch

  6. #6
    Senior Member Two Rings slideitsidewayz's Avatar
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    1998 Audi A4 1.8tqm gt2871r
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    Quote Originally Posted by Seerlah View Post
    This mod should work with just about any vehicle. I am not sure how advanced monitoring systems get (as in sensitivity), but B6 guys can do this 2.8 guys, B5 S4 guys, etc. If you are doing this mod because you have a turbo-back exhaust (no catalyctic converter), you wil need to place 2 non-foulers onto the secondary 02 sensor bung.

    This mod is essentialy the same thing as purchasing this: Clicky Click
    AWESOME! thanks dude...yeah i looked at my car before and i have an O2 sensor right after the turbo...so thanks for answering my question before i asked it lol.

  7. #7
    Veteran Member Four Rings Seerlah's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    You don't place this onto the sensor right after the turbo (this is called the primary 02 sensor). You place this on the secondary 02 sensor (downstream 02 sensor).
    I hate it when my car acts like a little bitch, treating me like the bitch

  8. #8
    Senior Member Two Rings SnowBum124's Avatar
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    1999.5 A4 1.8t avant
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    seattle

    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    ya i did that over a year ago and it worked great
    BetaAlphaTau member # 40

    love my shag-in wagon
    GT2871R turbo, 630cc genesis injectors, 034 Downpipe, SPAmanifold, TR11 FMIC, Maestro7, custom 3' intake/ heatsheld, south bend stage 4

  9. #9
    Senior Member Three Rings Fink_tha_Audi's Avatar
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    99.5 Audi A4 1.8t Q
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    Dover, Delaware

    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    Quote Originally Posted by slideitsidewayz View Post
    should this work on an AEB engine? if so...im doing this tomorrow! haha....good write up!
    it works on an AEB cuz I did the exact same thing for AEB A4, same parts and everything, I got a Labree HFC and this mod works great no CEL at least regarding the O2 sensor. Great write up.
    99.5 A4 1.8 TQM
    Eliminator GT2871R, UNITRONIC "440cc" tune, FMIC, 2.5" exhaust, SB Stg 4, Gutted LaBree, B&M short shifter, 034 Snub Mount, AWE DTS, LLTEK FR Strut Bar, Synapse DV, SCAT Rods, 034 HF Exhaust Manifold

  10. #10
    Veteran Member Four Rings Euromike's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    Sorry to thread resurrect, but i have a few questions. Im going to have my exhaust redone on my 2.8 30v. im taking stainless pipe straight from the block to the muffler. i cannot have CEL's, cause i have to pass emissions.

    So. on a 2.8 30v, where do i need these things? How many do i need? Is it a matter of drilling and tapping and threading them into the pipe? or welding them on somehow?

    i really need some help and imput. i gotta have this done soon, and i gotta tell the guy whos doing it what todo so i dont end up with a car that wont pass inspection. THANKS
    12' Tornado Red GTI DSG
    07' 2500HD Silverado 4x4
    99' Laser Red B5 A4 QM SOLD :(

  11. #11
    Veteran Member Four Rings Seerlah's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    So, you are removing your catalyctic converters and am making a header back exhaust (in a nutshell)? If this is correct, you would need to have your welder install 4 02 sensor bungs in total in the same place they would have been on your stock exhaust system. You will need 2 bungs on each side. One where the pre-cat bung used to be and one where the post-cat bung used to be. I am not too fluent on how the 2.8 will react, so I would suggest you go a different route (just a suggestion).

    Check out this link. You would need "2" regular 02 sensor bungs to be welded onto the straight pipe for the primary 02 sensors (bank 1 and bank 2), as I mentioned above at the correct spots. Then "2" of the j-piped sensor bungs to be welded in for the secondary 02 sensor bungs (bank1 and bank 2).

    You would also want to look into your state emission laws to see if a visual inspection of the catalyctic converters are required for the smog test. In my state, emission tests are simply done via OBD II port and I can fail 1 readiness (I need to pass 9/10). But they also do a visual test of a catalyctic converter. So I can pass my readiness, but would still fail emisssions (in your case) test do to not being able to pass the visual test. They just need to see that I actually have one.
    I hate it when my car acts like a little bitch, treating me like the bitch

  12. #12
    Veteran Member Four Rings Euromike's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    Quote Originally Posted by Seerlah View Post
    So, you are removing your catalyctic converters and am making a header back exhaust (in a nutshell)? If this is correct, you would need to have your welder install 4 02 sensor bungs in total in the same place they would have been on your stock exhaust system. You will need 2 bungs on each side. One where the pre-cat bung used to be and one where the post-cat bung used to be. I am not too fluent on how the 2.8 will react, so I would suggest you go a different route (just a suggestion).

    Check out this link. You would need "2" regular 02 sensor bungs to be welded onto the straight pipe for the primary 02 sensors (bank 1 and bank 2), as I mentioned above at the correct spots. Then "2" of the j-piped sensor bungs to be welded in for the secondary 02 sensor bungs (bank1 and bank 2).

    You would also want to look into your state emission laws to see if a visual inspection of the catalyctic converters are required for the smog test. In my state, emission tests are simply done via OBD II port and I can fail 1 readiness (I need to pass 9/10). But they also do a visual test of a catalyctic converter. So I can pass my readiness, but would still fail emisssions (in your case) test do to not being able to pass the visual test. They just need to see that I actually have one.
    Appriciate the imput!

    Well, honestly the only thing im trying to avoid is the extreme rusting of a traditional exhaust system. I thought removing the cats was a good idea due to them going bad and restricting flow, but if its a bad idea, just forget it. I just have to find a way to go stainless.
    12' Tornado Red GTI DSG
    07' 2500HD Silverado 4x4
    99' Laser Red B5 A4 QM SOLD :(

  13. #13
    Veteran Member Four Rings Seerlah's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    You can always have a system built with high flow catalyctic converters installed. I find a complete exhaust system to be really enjoyable on a vehicle. It grants a way better throttle response than the stock system can ever grant. Maybe still go the custom 2.5" route, and just have the high flow catalyctic converters installed. And still do as I mentioned above.

    http://vibrantperformance.com/catalo...b2518f861a6a37

    There is nothing wrong with having the cat converters removed, if that is what you want. It decreases back pressure, but at the cost of increased noise and cabin drone. The main thing to take into consideration is your state emission laws. For example, I live in NY and am required to have a cat converter during inspection. Just as the next, I eventually want a BT. I will have a 3" HFC welded into the dp, and that should grant me no issues to passing emissions in my state.
    I hate it when my car acts like a little bitch, treating me like the bitch

  14. #14
    Veteran Member Four Rings gmx's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    Just a question, I wonder how you get a wrench all the way down there?

    My hands/forearms aren't that big and I can hardly get mine down there for the WB install.
    NB: We don't have secondary O2s, so I'm using this bung for my WB.

    Did you have to remove the PCV hard line and/or airbox?
    00 A4 1.8TQ MT (AJL)

    17*8 BBS RK | Vogtland GT 575F/675R | H-Sport Sways | 320mm B8 Brakes, 300mm rear |
    GT2871R Elim | Maestro tuned AJL | 034 3" HFC | Milltek | 034 TIP[bin] | JHM SSK
    3090lbs

  15. #15
    Veteran Member Four Rings Seerlah's Avatar
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    Re: DIY: Non-Fouler Mod to Remove CEL for Test Pipe or High Flow Cat

    Yeah, I removed the top portion of the airbox.
    I hate it when my car acts like a little bitch, treating me like the bitch

  16. #16
    Deactivated Two Rings Broccolihash's Avatar
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    Completed this mod last weekend! Works great so far!

  17. #17
    Senior Member Two Rings a4_1.8t_01's Avatar
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    This doesn't work on my AWM a4 since my 02 is longer than the one you have. I would need a longer part to work on mine.
    Unitronic tuned. love it.

    Need any services done in NYC area please PM me. I will diagnose and fix your car. Also do clutch replacements, Timing-belt services, Turbo upgrade/installation, Fluid changes, boost leaks and pretty much anything.

  18. #18
    Veteran Member Four Rings Seerlah's Avatar
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    I have an AWM and have 2 spacers currently on mine. I got tired of having be cautous of the way I drive, to avoid a CEL with one non-fouler. Oh, the freedom of cruising in 3rd gear for as long as I want.
    I hate it when my car acts like a little bitch, treating me like the bitch

  19. #19
    Veteran Member Four Rings jturnbull's Avatar
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    Quote Originally Posted by gmx View Post
    Just a question, I wonder how you get a wrench all the way down there?

    My hands/forearms aren't that big and I can hardly get mine down there for the WB install.
    NB: We don't have secondary O2s, so I'm using this bung for my WB.

    Did you have to remove the PCV hard line and/or airbox?
    Its a pain in the ass put a open box wrench on there take a pipe and bash it loose. Thats how i did mine

  20. #20
    Veteran Member Four Rings k0mpresd's Avatar
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    Quote Originally Posted by a4_1.8t_01 View Post
    This doesn't work on my AWM a4 since my 02 is longer than the one you have. I would need a longer part to work on mine.
    a hexedit mod would work. ;) hit me up.
    self tuned.

  21. #21
    Veteran Member Four Rings alen's Avatar
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    Quote Originally Posted by k0mpresd View Post
    a hexedit mod would work. ;) hit me up.
    You don't have the same mod for ATW? I have the spacer (it's baked in after several years of being there) and I have the occasional code pop up. I'd be so relieved to have it gone forever.

  22. #22
    Veteran Member Four Rings k0mpresd's Avatar
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    sent pm.
    self tuned.



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