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  1. #1
    Active Member One Ring
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    Jun 30 2014
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    Canada

    O2 Sensor Questions

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    Hey everybody, sorry if this is the wrong place to post this, but I'm looking at picking up a 2005 S4 that has a few issues for quite the bargain. Seller has provided me with the following codes which are related to the O2 sensors, and I want to ask if anyone has experienced this/knows how to fix this.

    16420 / P0036: O2 sensor bank 1 sensor 2 heating circuit malfunction/open circuit, no signal/no communication
    17522 / P1114: O2 sensor bank 1 sensor 2 internal resistance too high , no signal/no communication
    16440 / P0056: O2 sensor bank 2 sensor 2 heating circuit malfunction/open circuit, no signal/no communication
    17548 / P1140: O2 sensor bank 2 sensor 2 internal resistance too high , no signal/no communication

    Is this a failure of a single sensor, or does this point to any deeper electronics issues? Does this indicate something that I should run, not walk away form?

    I've tried my hand at some google-fu, but I wasnt able to dig up any answers on this specific set of codes. I appreciate any advice you can give me. Thanks!

  2. #2
    Senior Member Three Rings MugelloB7RS4's Avatar
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    Feb 06 2015
    AZ Member #
    313804
    Location
    Toronto

    These codes are for two different sensors. They are for the O2 sensors after that cat on both sides. It almost makes me wonder if they're connected or not. That's where I would start. Heater circuit and too high of resistance and no comm seems like they might be disconnected.

  3. #3
    Veteran Member Three Rings
    Join Date
    May 18 2012
    AZ Member #
    93721
    My Garage
    2005 S4
    Location
    Portland, OR

    Quote Originally Posted by MugelloB7RS4 View Post
    These codes are for two different sensors. They are for the O2 sensors after that cat on both sides. It almost makes me wonder if they're connected or not. That's where I would start. Heater circuit and too high of resistance and no comm seems like they might be disconnected.
    Yeah, those codes indicate that the sensors are disconnected. Being that they are the post-catalyst O2 sensors they should not affect how the car runs. Those sensors CAN be coded out, but unless you're running catless there's really no reason that they shouldn't be functional unless they get damaged.

  4. #4
    Active Member One Ring
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    Jun 30 2014
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    That clears some confusion up, thanks!

    So if both sensors are tripping codes, it sounds more like a connection issue than the sensors themselves failing. Is there a common point where there could be a connection issue between both sensors? Maybe a connection in the ECU/a fuse?

    If those were deliberately disconnected, are there serious issues that it could be concealing?

  5. #5
    Established Member Two Rings PigDiesel54's Avatar
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    Jan 18 2013
    AZ Member #
    107784
    Location
    CT

    Here's the location of where the 02 sensors get plugged into on the firewall. The other side is obviously on the downpipes. Checking those connections is a start.
    Screenshot_20180612-123217_Chrome.jpeg
    2006 Brilliant Red B7 S4 Avant 6MT
    2001 Cactus Green B5 S4 Avant 6MT
    2006 Brilliant Red B7 A4 2.0T Quattro Tiptronic

  6. #6
    Veteran Member Four Rings mad70sx's Avatar
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    Mar 12 2009
    AZ Member #
    39786
    My Garage
    Silver '04 S4
    Location
    Lil Rhody

    Or the O2 sensors themselves are faulty.
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  7. #7
    Veteran Member Three Rings
    Join Date
    May 18 2012
    AZ Member #
    93721
    My Garage
    2005 S4
    Location
    Portland, OR

    Quote Originally Posted by mad70sx View Post
    Or the O2 sensors themselves are faulty.
    They could be, but I just find it unlikely that both would have failed on both the heater and the main circuits especially with an "open circuit" error. In any case, checking the connections should be the first step regardless.

  8. #8
    Veteran Member Four Rings evildsmr's Avatar
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    Sep 13 2012
    AZ Member #
    100451
    My Garage
    96 VR6
    Location
    denver

    I agree. This seems like they are unplugged. S2 aren't that special anyways. So I'd say send it.

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  9. #9
    Senior Member Four Rings ven0m's Avatar
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    May 10 2015
    AZ Member #
    332001
    Location
    Slovenia

    Quote Originally Posted by 924Carrera View Post
    They could be, but I just find it unlikely that both would have failed on both the heater and the main circuits especially with an "open circuit" error. In any case, checking the connections should be the first step regardless.
    Agreed, normaly they fail with "short to ground", not 2x "open circuit".
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  10. #10
    Veteran Member Four Rings mad70sx's Avatar
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    Mar 12 2009
    AZ Member #
    39786
    My Garage
    Silver '04 S4
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    Lil Rhody

    Quote Originally Posted by 924Carrera View Post
    They could be, but I just find it unlikely that both would have failed on both the heater and the main circuits especially with an "open circuit" error. In any case, checking the connections should be the first step regardless.
    Quote Originally Posted by ven0m View Post
    Agreed, normaly they fail with "short to ground", not 2x "open circuit".
    Having had a chance to read into it more, I also agree.
    JHM Tune ~ JHM Version 2 Headers ~ FI/JHM 2.5" Exhaust ~ Bilstein PSS9 Coilovers ~ BBS CH

  11. #11
    Active Member One Ring
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    Thanks for all the help guys!

  12. #12
    Veteran Member Four Rings mad70sx's Avatar
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    Mar 12 2009
    AZ Member #
    39786
    My Garage
    Silver '04 S4
    Location
    Lil Rhody

    Quote Originally Posted by Chaggot View Post
    Thanks for all the help guys!
    Got it sorted out? What did you find?
    JHM Tune ~ JHM Version 2 Headers ~ FI/JHM 2.5" Exhaust ~ Bilstein PSS9 Coilovers ~ BBS CH

  13. #13
    Active Member One Ring
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    Quote Originally Posted by mad70sx View Post
    Got it sorted out? What did you find?
    I think I'm going to hold off on making an offer on this car unless the seller drops his price further.

    Among the O2 sensor issue, the car also has issues with the ABS system, and apparently the owner had installed solid motor mounts in an attempt to rectify a vibration issue (?).

    After looking through a bunch of the DIYs on here, I feel confident that I'd be able to swap the mounts out for something more comfortable (likely 034 Street density), as well as figure out the ABS system for minimal cash investment. I was unsure about what the o2 sensor codes were indicating, hence this thread.

    https://www.kijiji.ca/v-cars-trucks/...ationFlag=true

    This is the car in question. KMs are kinda up there as well, but this could be a fun little project for the time being. I currently have an 05 A4, so I'm fairly familiar with the B6 platform and some of the other frustrations to be aware of.



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