P0420 & TechStream - Troubleshoot O2 sensors?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by maverick1970, Apr 25, 2015.

  1. maverick1970

    maverick1970 Junior Member

    Joined:
    Apr 24, 2011
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    Location:
    McDonough, GA
    Vehicle:
    2007 Prius
    Model:
    Two
    I have the P0420. I removed both O2 sensors and cleaned them hoping that would help but it didn't. I have used TechStream and recorded the values of the two sensors while driving. I am not sure if the sequence between the RPMs and the voltage measurements mean anything. It looks like there maybe something wrong but can't pin point it.

    See attached of the actual code from Techstream. CATALYST EFFICIENCY FAILED O2 STORAGE B1.PNG

    Is there a way to troubleshoot the sensors, because I want to find out if my issue is potentially with a sensor and not the CAT.

    Top graph is engine RPMs
    Middle graph is AF Sensor
    Bottom graph is O2 Sensor

     
    #1 maverick1970, Apr 25, 2015
    SFO and blaisep like this.
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
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    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Was the engine fully warmed up prior to your taking those readings? If yes then the A/F ratio sensor needs to be replaced since it shows almost no voltage variation over time - when engine speed is held constant at around 2,500 RPM.
     
    #2 Patrick Wong, Apr 25, 2015
    SFO, blaisep and maverick1970 like this.
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