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2008 Prius aftermarket cat and o2 sensor running too rich

Discussion in 'Gen 2 Prius Technical Discussion' started by oracle100, Jan 25, 2021.

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  1. oracle100

    oracle100 Kaizen

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    Had my CAT and o2 sensor stolen from my 2008 Prius with 170k miles. I replaced it with an eBay cat and universal o2 sensor. Now I'm getting a check engine light p0172 and p0101. Engine seems to be running rich and sometimes rough when idling. I've tried the cheaper Denso o2 sensor from Amazon.
    .
    Still get a CEL. Any suggestions?
     
    #1 oracle100, Jan 25, 2021
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    Well, the MAF sensor is the major input to the ecu to determine how much fuel to inject. I would go after the P0101 code. Look in the service manual. Remove and inspect the sensor for damage and contamination, check the wiring.

    what does the MAF display in gram/sec at idle(list how many rpm) , and what are the short and long term fuel trims?

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, Jan 27, 2021
  3. oracle100

    oracle100 Kaizen

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    I forgot to mention I replaced the MAF couple of weeks ago with OEM, there were no damage to the wires, drove 230 miles and still getting the same codes.
     
    #3 oracle100, Jan 27, 2021
  4. SFO

    SFO Senior Member

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    Address the P0172 first, then the P0101.

    Here is the workup for DTC P0172 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/2054m/cip0171.pdf

    Here is the workup for DTC P0101 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/2054m/cip0101.pdf

    You've now replaced the new 'universal' upstream sensor with the appropriate upstream A/F Denso unit?

    Which OBD2 code scanner are you currently using?

    Do you have a multi-meter to test with?
     
    #4 SFO, Jan 27, 2021
  5. oracle100

    oracle100 Kaizen

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    I have the OEM upstream o2 sensor and Generic Universal (non-Deso) downstream. I tried the Alternative Denso downstream o2 sensor (Denso 234-4623) from Amazon and gave me the same results, so I returned it. The MAF is new OEM. I do have a multi-meter and a cheap Harbor Freight ODB2 scanner. The catalytic converter is generic form eBay.
     
    #5 oracle100, Jan 27, 2021
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