1. Attachments are working again! Check out this thread for more details and to report any other bugs.

O2 Sensor Locations

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by priusde, Aug 6, 2016.

  1. priusde

    priusde Junior Member

    Joined:
    Mar 22, 2016
    28
    5
    0
    Location:
    DE
    Vehicle:
    2010 Prius
    Model:
    II
    Trying to replace the post cat O2 but not sure if I have the right location. Anyone have a diagram?
     
    #1 priusde, Aug 6, 2016
  2. NutzAboutBolts

    NutzAboutBolts Senior Member

    Joined:
    Mar 5, 2013
    1,476
    1,552
    0
    Location:
    Bay Area
    Vehicle:
    2012 Prius
    Model:
    Four
    It should be after the cat and there should be only 1 after the cat.
     
    #2 NutzAboutBolts, Aug 6, 2016
  3. priusde

    priusde Junior Member

    Joined:
    Mar 22, 2016
    28
    5
    0
    Location:
    DE
    Vehicle:
    2010 Prius
    Model:
    II
    Is this it (photo)? It's the only one I see and it appears to be before the cat.
     

    Attached Files:

    #3 priusde, Aug 6, 2016
  4. Raytheeagle

    Raytheeagle Senior Member

    Joined:
    Jul 1, 2016
    11,251
    15,482
    0
    Location:
    Bay Area, California
    Vehicle:
    2019 Prius Prime
    Model:
    Prime Plus
    That appears to be the one before the cat. Look further back along the exhaust and it will look similar. Any reason for replacing the oxygen sensor after the cat? Rarely any issues with that sensor. Usually the one in front of the cat has more problems.
     
    #4 Raytheeagle, Aug 6, 2016
  5. priusde

    priusde Junior Member

    Joined:
    Mar 22, 2016
    28
    5
    0
    Location:
    DE
    Vehicle:
    2010 Prius
    Model:
    II
    About how far back after the cat should it be because am not seeing it.

    Old engine had big head gasket leak, probably ended up fouling the cat. It's throwing the PO420 code and I wanted to put on a spacer to pass emissions before spending big money on a factory cat.
     
    #5 priusde, Aug 6, 2016
  6. Raytheeagle

    Raytheeagle Senior Member

    Joined:
    Jul 1, 2016
    11,251
    15,482
    0
    Location:
    Bay Area, California
    Vehicle:
    2019 Prius Prime
    Model:
    Prime Plus
    Away from my house now, but will snap a shot when I get back. How many miles on her before the head gasket went? Any idea what the cause was?
     
    #6 Raytheeagle, Aug 6, 2016
  7. Raytheeagle

    Raytheeagle Senior Member

    Joined:
    Jul 1, 2016
    11,251
    15,482
    0
    Location:
    Bay Area, California
    Vehicle:
    2019 Prius Prime
    Model:
    Prime Plus
    .
     
    #7 Raytheeagle, Aug 6, 2016
    Last edited: Aug 6, 2016
  8. priusde

    priusde Junior Member

    Joined:
    Mar 22, 2016
    28
    5
    0
    Location:
    DE
    Vehicle:
    2010 Prius
    Model:
    II
    Not sure exactly what it was as I bought the car this way from previous owner at 230k. I just ended up replacing the engine.
     
    #8 priusde, Aug 6, 2016
    Raytheeagle likes this.
  9. Raytheeagle

    Raytheeagle Senior Member

    Joined:
    Jul 1, 2016
    11,251
    15,482
    0
    Location:
    Bay Area, California
    Vehicle:
    2019 Prius Prime
    Model:
    Prime Plus
    Reliving at
    After looking under the hood, the upstream oxygen sensor can be reached by removing the wipers from above or probably from underneath by removing the splash guard.

    The picture you took earlier looks like it was from underneath looking toward the front of the car.

    That should be the downstream oxygen sensor as the cat is in front of it and the resonator is downstream of it. Hope it solves the code for you. On eBay or a salvage yard you probably could get a cheaper cat and exhaust setup. Sounds like you are familiar with that though:).
     
    #9 Raytheeagle, Aug 6, 2016
  10. priusde

    priusde Junior Member

    Joined:
    Mar 22, 2016
    28
    5
    0
    Location:
    DE
    Vehicle:
    2010 Prius
    Model:
    II
    Aha so that is the post cat, lol. Too dark now but will get at it tomorrow, thanks for the help.
     
    #10 priusde, Aug 6, 2016
(You must log in or sign up to post here.)