2nd Gen R56 Cooper S Is the P0420 error a true catalyst failure?

Discussion in '2nd Generation: 2007+ R55 through R61' started by genik, Jul 14, 2016.

  1. genik

    genik Member

    Feb 20, 2012
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    Ive got a P0420 code appearing on a scan plus a check engine light. Is there any chance that its not a catalyst failure and that it might be something else i need to check?
     
  2. Guapish_Fliver

    Guapish_Fliver New Member

    May 31, 2016
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    I don't think the car is being coy...

    What makes you think it's something else when the code is for cats?

    That's the same code I got when I hacked them out...

    You could spend some guap replacing them, or save some guap deleting them...

    That code is telling you it's time to start modding..
     
  3. Dave.0

    Dave.0 Helix & RMW Powered
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    It could be a faults reading from one of your O2 sensors. (you have two) :idea:

    Take them our and switch them ( Pre Cat and Post Cat) and clear all adaptations and test by driving around for a few hundred miles.

    I really do not think you CAT has failed at all. CAT failures are very rare.
     
  4. Guapish_Fliver

    Guapish_Fliver New Member

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    Not as rare as u think, I kilt my cats when my car was sucking oil...

    The first cat in the dp gets hella dirty :shocked:

    Wouldn't bad o2 sensors throw an o2 sensor code?

    I thought po420 had to do with pressure differentials between o2 sensors right?
     
  5. DneprDave

    DneprDave Well-Known Member
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  6. ZippyNH

    ZippyNH Well-Known Member

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    No psi sensors on a 02 sensor....
     
  7. Dave.0

    Dave.0 Helix & RMW Powered
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    Yup, the first O2 looks to be failing or failed.
     
  8. ZippyNH

    ZippyNH Well-Known Member

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    How is your oil consumption ?
    Many times a turbo fails....often with a leaking seal...and it DOES cover the cat with oil....
    Think you had a failing turbo thread?

    And the check-engine light is CAUSED by the cat code...how else would you know too check it?!
    Ouch......just have to say it...what have you been drinking? It must be pretty strong!
     
  9. Guapish_Fliver

    Guapish_Fliver New Member

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    #9 Guapish_Fliver, Jul 14, 2016
    Last edited: Jul 14, 2016
    Ya bad turbo seals can kill your cat. Or bad valve guides, rings, cylinders, and pcv.

    My car had all of the above and my cat died. Dead.

    Your primary cat sits directly underneath, very close to the turbo and is known to kill seals due to back pressure. They also create massive heat in that little hell tunnel. Might want to consider ending the cats before they end your cash flow. Your cat is plotting to kill your turbo as we speak

    U could get a catless dp and a tune for around the same price as OEM replacement. :ihih:
     

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  10. Dave.0

    Dave.0 Helix & RMW Powered
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    This is a how you can tell if you have a dead cat.

    Look for the tracks.

    [​IMG]
     
  11. genik

    genik Member

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    As a symptom, what would you say that occurs?
    For me, i have noticed that there is a power loss, especially at high speeds (over 100km/h) also when i floor it, i can hear the sound as it its reving but the power out come will not show up!
    Anyone that had the issue with the same symptoms?
     
  12. DneprDave

    DneprDave Well-Known Member
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    If your catalytic converter is plugged, you will have loss of power.

    As I remember you had a noisy turbocharger, a bad seal in the turbo will leak oil all over the inside of the catalytic converter and plug it up when the oil burns inside the cat.

    Did you ever change out your turbocharger?.
     
  13. genik

    genik Member

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    Nope not yet, what exactly do you mean that might be happening?
     
  14. DneprDave

    DneprDave Well-Known Member
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    Oil leaking through a bad turbocharger seal has nowhere else to go but through the catalytic converter.
    That oil will burn up in the catalytic converter and reduce flow, causing performance problems.
     
  15. Guapish_Fliver

    Guapish_Fliver New Member

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    The back pressure on the exhaust turbine from the cat will wear the pressure seals paper thin. If you wait too long to change a bad turbo, the turbine will eventually crash the housing and splode...
     
  16. genik

    genik Member

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    What should i check (u know signs) that will make this malfunction a certainty?
     
  17. Firebro17

    Firebro17 Dazed, but not Confused
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    Hmmm.... A 420 code ya say there Genik? That tells me your car's been smok'n somethin funny! :sosp:

    Or, maybe just the driver.
     
  18. Guapish_Fliver

    Guapish_Fliver New Member

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    Play in the turbo shaft...

    The fact that your car has already told you via check engine light...

    If your not already certain just forget about it and wait for it to frag. :Thumbsup:
     
  19. MCS02

    MCS02 Moderator
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    genik I understand when we give an answer you may need to ask a follow up question or two if you don't understand, that's ok. But at times it seams you want us to tell you what is wrong with the car with certainty. We can't do that over the internet. We have to go off the information you give us. To know with certainty we would have to have the car in front of us. On some problems you will have to tare into the motor to find what is wrong for sure.
    This is one of those times. Do you do any of the work on your car yourself? If so how much can you do? I believe you said it's hard to get the car worked on where you live.
     
  20. DneprDave

    DneprDave Well-Known Member
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    The turbocharger is easy to check. Take the turbocharger end of the rubber air intake hose loose from the turbocharger and grab the end of the compressor wheel, it should spin easily but you should not be able to move it in any other direction. If there is any other movement, in and out, up and down or side to side, then your turbocharger is bad and needs to be replaced.
     

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