O2 sensor fell off Triangle of death and other lights on dash now

Discussion in 'Gen 2 Prius Main Forum' started by Ilovemystinkingprius, Dec 23, 2024 at 10:18 AM.

  1. Ilovemystinkingprius

    Ilovemystinkingprius New Member

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    So my o2 sensor fell off on the freeway. I was able to get home and replace the part. I have the triangle of death, my car wont go into drive, my engine wont turn over, my gas is full but it keeps saying it's empty. ABS, VSC lights are on. I have a 2007. I'm curious if anyone has delt with this or may know a solution. I am just trying to figure out how to get my engine to turn over. Or something. IMG_4042.jpeg IMG_4013.jpeg
     
    #1 Ilovemystinkingprius, Dec 23, 2024 at 10:18 AM
  2. Brian1954

    Brian1954 Senior Member

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    The first thing to do is read the trouble codes.

    It sounds like your car has a couple of unrelated problems.
     
    #2 Brian1954, Dec 23, 2024 at 7:52 PM
    Last edited: Dec 23, 2024 at 10:27 PM
  3. ChapmanF

    ChapmanF Senior Member

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    I want the rest of the "sensor fell off" story!

    That is a heated oxygen sensor, so the four wires include a power supply to the sensor's heater. If those wires get torn apart when the sensor falls off, and the heater power happens to touch something grounded, it can sometime blow a fuse, sometimes damage a power transistor inside the ECM, sometimes both, resulting in trouble codes and strange behavior.

    I think most reports of this have been from owners whose entire catalytic converters have, ahem, fallen off. Is there any chance someone was trying to liberate your catalytic converter, maybe got interrupted?
     
    #3 ChapmanF, Dec 23, 2024 at 10:40 PM
  4. Hayslayer

    Hayslayer Junior Member

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    have to agree with the above. Likely a short circuit due to those shredded wires popped a fuse or damaged something.

    If I remember right, it gets power from the 15A EFI fuse in the underhood fuse box. Provides power to engine control and hybrid control systems. I'm not sure how the car would have continued to run if that fuse popped, but maybe it popped the fuse after you got home and started working on it. Would be great if that's your problem.
    Pull the cover off and it should be the 15A fuse at the top right corner.
    There should be a spare 15A fuse near the top center of the fuse box
     
    #4 Hayslayer, Dec 24, 2024 at 12:44 AM
    Last edited: Dec 24, 2024 at 1:06 AM
  5. Ilovemystinkingprius

    Ilovemystinkingprius New Member

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    Okay so a bit of an update I used the OB sensor to check the codes and the code that is popping up is UO100 "Lost communication with ECM/PCM A". Not sure what this means either. I am going to check the fuses. I knew there was a problem previously with my O2 sensor I guess somehow it got loose because when it fell off there was banging on the bottom of my car. I was able to Pull off the freeway and park within 5 mins before getting towed and after I tried to pull into my garage my car would only go into Neutral.
     
    #5 Ilovemystinkingprius, Dec 24, 2024 at 10:33 AM
  6. Ilovemystinkingprius

    Ilovemystinkingprius New Member

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    I will do this today and let you know if it works!
     
    #6 Ilovemystinkingprius, Dec 24, 2024 at 10:34 AM
  7. ChapmanF

    ChapmanF Senior Member

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    That power to the heater is controlled by a power transistor inside the ECM. There used to be a list of "Murphy's Law Corollaries" that got passed around in techie shops, and one of them was "a transistor that is protected by a fast-blowing fuse will protect the fuse by blowing first".

    Doesn't always happen, but if it does, I think there's a trouble code for it. If the transistor is kaput, the ECM is needed.

    Found this in a gen 3 repair manual, but haven't checked if it's the same in gen 2:

    [​IMG]
     

    Attached Files:

    #7 ChapmanF, Dec 24, 2024 at 12:17 PM
  8. Ilovemystinkingprius

    Ilovemystinkingprius New Member

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    I have fixed it! Thank you everyone who helped and sent advice. It was the 15A EFI fuse that needed to be replaced. I don't know why I didn't think of a fuse in the first place haha. But once again thank you all. I appreciate it greatly!
     
    #8 Ilovemystinkingprius, Dec 24, 2024 at 2:12 PM
  9. Hayslayer

    Hayslayer Junior Member

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    The ecm also receives power from the EFI fuse. Good luck, hope you get it sorted out.

    And because I'm bored while waiting for our guests to arrive this evening:

    In simple terms.
    EFI fuse outlet splits to two wires.

    One goes to the ECM pin 6 labelled BATT

    The second supplies the EFI M relay, whose output wire then splits to 5 wires at Junction Connector J1.
    1. supplies cannister purge module pin 9 (vent valve) and fuel vapor containment valve
    2. ECM at pin 4 labelled +B
    3. MAF meter pin 1 +B, the purge valve, and the air/fuel ratio sensor B1S1 +B
    4. Oxygen sensor B1S2 +B
    5. the fuel pump via relay
     
    #9 Hayslayer, Dec 24, 2024 at 6:25 PM
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