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Prius P0420 Code - Bad Cat. Converter?

Discussion in 'Gen 2 Prius Technical Discussion' started by Bryan Holloway, Jun 23, 2016.

  1. Bryan Holloway

    Bryan Holloway Junior Member

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    Location:
    Fullerton, Ca
    Vehicle:
    2006 Prius
    Model:
    II
    I have this code. I have checked the live data with my reader and am trying to diagnose this to see if it could save me a catylitic converter. I just dont know what to look for in the live data. This shot was taken with engine warm at 2500 RPM. I also measured the inlet and outlet with a thermal temp gauge of the converter and temp seemed about the same.


     
    #1 Bryan Holloway, Jun 23, 2016
  2. Bryan Holloway

    Bryan Holloway Junior Member

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    Location:
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    Vehicle:
    2006 Prius
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    II
    #2 Bryan Holloway, Jun 23, 2016
  3. S Keith

    S Keith Senior Member

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    If you can monitor you downstream O2 sensor and see erratic readings or high voltage, you can confirm P0420.
     
    #3 S Keith, Jun 23, 2016
  4. Bryan Holloway

    Bryan Holloway Junior Member

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    Location:
    Fullerton, Ca
    Vehicle:
    2006 Prius
    Model:
    II
    So my upstream is "O2S B1 S1(V)" and its pretty constant around 3.3V as seen in the video, which is really high correct? I read its supposed to be below 1V. Does that indicate a bad sensor, or lean mixture or something?

    The downstream "O2S B1 S2(V)" seems to jump between .2-.4. But my reader isn't really "live" it just updates every few seconds.
     
    #4 Bryan Holloway, Jun 23, 2016
    Last edited: Jun 23, 2016
  5. Bryan Holloway

    Bryan Holloway Junior Member

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    Location:
    Fullerton, Ca
    Vehicle:
    2006 Prius
    Model:
    II
    Anybody able to help me with this issue? I need to fix asap as i need to renew the registration =(
     
    #5 Bryan Holloway, Jun 24, 2016
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    3.3V is correct. That indicates an air/fuel ratio of 15 to 1 which is nominal. The first sensor is an air/fuel ratio sensor, not an oxygen sensor.

    You need to replace the catalytic converter.
     
    #6 Patrick Wong, Jun 24, 2016
    Bryan Holloway likes this.
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