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Thread: P2096 is being persistent. (Downstream O2 sensor)

  1. #31
    Senior Member klroger's Avatar
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    I'll have to go back & read the whole thread. I don't know if an exhaust leak after the converter will effect the Cat monitor... Do your O2 sensor readings & your Cat monitor reading voltages look about the same, or is the O2 reading cycling with the Cat monitor reading steady voltage in a hot engine running in closed loop???


    I didn't know what to do, so I didn't do anything

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        click to view fuel log View my fuel log 2018 Mirage GT 1.2 automatic: 37.3 mpg (US) ... 15.9 km/L ... 6.3 L/100 km ... 44.8 mpg (Imp)


  2. #32
    Senior Member Cani Lupine's Avatar
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    I'm pretty sure the leak is allowing fresh air to be sucked in, which intermittently affects the downstream O2 sensor readings.

    My UltraGauge doesn't show the upstream voltage, only the lambda value, but comparing the lambda to the downstream voltage seems to show that both sensors are reading near identical. They both show the car is running rich most of the time.

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        click to view fuel log View my fuel log 2014 Mirage DE 1.2 manual: 49.2 mpg (US) ... 20.9 km/L ... 4.8 L/100 km ... 59.1 mpg (Imp)


  3. #33
    Senior Member Cani Lupine's Avatar
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    Whelp, the exhaust leak I fixed didn't get the code to go away, so either there's another leak I haven't found or it might be the catalytic converter going bad.

    I did have P0421 come back up in pending as well as P2096, so that's pointing more to a cat failure.

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        click to view fuel log View my fuel log 2014 Mirage DE 1.2 manual: 49.2 mpg (US) ... 20.9 km/L ... 4.8 L/100 km ... 59.1 mpg (Imp)


  4. #34
    Senior Member klroger's Avatar
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    If both upstream & down stream sensors read the same, you Do need a converter. If it's running rich, (high voltage) there's the cause of the converter failure...
    I didn't know what to do, so I didn't do anything

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        click to view fuel log View my fuel log 2018 Mirage GT 1.2 automatic: 37.3 mpg (US) ... 15.9 km/L ... 6.3 L/100 km ... 44.8 mpg (Imp)


  5. #35
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    Cani Lupine - I'm going to go back and read this thread again (at least your entries) to see if I might agree that a bad cat could be contributing. In any event, this thread is a heckuva good thread for the future members who run into this same issue. That's bound to happen.

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        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


  6. #36
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    Cani Lupine - You said you put in NGK Ruthenium spark plugs and NGK coil packs. When did you do that? Was it just before these problems?

    As to the running "rich." This is all speculation on my part. I have done my fair share of staring at a wideband gauge and carburetor tuning. But that doesn't make me an expert here. But my speculation is that those fuel trims you mention showing running sort of offset rich, that does tend to make sense with your ram air intake.

    Because, if your setup is able to get some amount more air into the cylinders, the ECU is programmed to try to achieve stoich. If there is more air, it would have to add more fuel. Maybe this is the reason for the fuel trims to show some offset rich, to match the additional air with gas.

    And ... this would lead to more power (more power baby). Perhaps this is why you feel like your car runs so well (after "learning").

    I can't say I (re)read anything from your analysis that would tend to make me think your cat is failing. But I've been wrong before. The only experience I've had with cat failure was in an old car I had, when the cat began plugging the exhaust flow (what could cause it to fail like this plugging the exhaust flow could be a bunch of reasons I suppose). That car idled good and performed well at low rpm. But at any real demand it would fall on its face with no power. I think if you can take your car to 5,500 rpm and it pulls strong at WOT to 6,000+ rpm (max flow), I tend to doubt your cat is failing. Of course, I suppose there are other ways for a cat to fail. It could just not catalyze I suppose. But that wouldn't result in a lean / rich problem I don't believe. The lamda 0.893 reading (or some number like that) I tend to doubt will have much negative impact on the cat. As noted above, you're getting extra air from your ram air setup very likely. So in the end, your burn AFR should be good and in the range to not damage a cat (speculation on my part again).

    I sort of mispoke about me saying I doubt your theories in one of my first replies. It wasn't accurate. It's not that I doubt your theories, all your posts seem to be very accurate to what I believe to be true. I just had my doubts that those theories were contributing to the code you were getting.

    Last thing - After doing your exhaust leak repair, did you reset the computer again to put it through it's learning procedure again?

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        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


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    Quote Originally Posted by Cani Lupine View Post
    I'm pretty sure the leak is allowing fresh air to be sucked in, which intermittently affects the downstream O2 sensor readings.

    My UltraGauge doesn't show the upstream voltage, only the lambda value, but comparing the lambda to the downstream voltage seems to show that both sensors are reading near identical. They both show the car is running rich most of the time.
    if both sensor are near identical in reading it means the cat is not efficient anymore so it could be a bad cat but judging by my experience with the mirage if o2 gone bad it doesn't have a reading anymore but yours still have, but you can test a rear o2 sensor if its cheaper than cat.

  8. #38
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    Something I've never thought of before - Does the ECM use O2 sensors to judge the effectiveness of a catalyst? That doesn't make sense to me, but that may be how it is. If so, I would imagine the post cat sensor should read more lean than the pre-cat ... I think. Meaning, after catalization there should be more oxygen in the exhaust. Just rambling as I'm unfamiliar.

        __________________________________________

        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


  9. #39
    Quote Originally Posted by klroger View Post
    If both upstream & down stream sensors read the same, you Do need a converter. If it's running rich, (high voltage) there's the cause of the converter failure...
    You're more O2 sensor smarter than I. I've never really learned much about reading this stuff...And now I'm stuck so I figured I'd hi-jack this and maybe get both of these turds figured out?

    I've got a 14 Silverado with a 6.2L that has high o2 sensor voltage readings on b1s1. When it's idling b1s1 is reading 1.7-1.84 volts while b1s2 shows between zero-.84 I pulled a canadian tire mechanic move and blindly replaced the b1s1 o2 sensor last week after getting a p015b and p0172. Now I'm getting a p0132,p0137,p0172 along with the occasional po420 and p2096. Fuel trims for bank 1 are -10 to -20. It'll run ok then start to miss and run like pooh. Me thinks the connector may be effered or have leaky injectors maybe? I think this turd may have direct injection, it's covered in plastic crap and I haven't dug into it yet.

    Then on the other side of the engine(bank 2) o2 sensor readings between front and rear sensors are pretty similar. Usually around .73 and .71 respectively. It's got about 120k on it and was bought used a few years ago. Body looks shiny but underneath looks like it's an old oilpatch truck.

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        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


  10. #40
    Senior Member AtomicPunk's Avatar
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    Quote Originally Posted by 7milesout View Post
    Something I've never thought of before - Does the ECM use O2 sensors to judge the effectiveness of a catalyst? That doesn't make sense to me, but that may be how it is. If so, I would imagine the post cat sensor should read more lean than the pre-cat ... I think. Meaning, after catalization there should be more oxygen in the exhaust. Just rambling as I'm unfamiliar.
    Yes, that's what the back O2 sensor does.



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