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Bought a 07 Prius, first I got a CEL, now the red triangle of death.

Discussion in 'Gen 2 Prius Technical Discussion' started by Bryce Paige, Aug 16, 2021.

  1. Bryce Paige

    Bryce Paige Junior Member

    Joined:
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    Location:
    Bay Area
    Vehicle:
    2007 Prius
    Model:
    N/A
    Just bought an 07 Prius last week. Drove fine on the test drive and I got no engine codes when I did a full scan of the system with my BlueDriver scanner. However, I naively trusted the guy and bought the car with a slightly expired smog certificate from about 4 months ago (CA resident). I bought the car and went to smog it the next day and was told the ECU had recently been reset (of course it had).

    I drove the car for another 20 miles before it gave me a P0420 code, I wasn't surprised at this point, but I was just praying it was an o2 and not the cat, considering that would cost what I just spent on this car. I did some research and found a video of a guy installing a o2 spacer in his gen2 Prius to temporarily circumvent the codes and get his car to pass inspection.

    I installed the spacer with the sensor but unfortunately didn't realize just how badly the sensor was rubbing against the heat shielding in the trans tunnel. This caused the wires to rub raw and rub directing against the tub of the Prius.

    I didn't notice this until I attempted to start the car after all of the this. I had disconnected the car at the ground point from the 12V battery. I reattached this point, and then when I started the car I was greeting by the red triangle and a car that would only go into neutral. I read the computer codes and got U0100 Lost communication with ECM/PCM 'A'. I tried removing the spacer and installing a new OEM o2 sensor today but got the same results plus an additional code, "P3000 Status: Current/History - Battery Control System"

    At this point I'm lost, I'm hoping I knocked some connection loose when disconnecting the battery or I shorted out some fuse when I messed up the o2 sensor, but I don't know where to start. If anybody has any advice on what I should start with that would be very helpful. Thank you!
     
  2. dolj

    dolj Senior Member

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    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    Probably this. Grab your ohmmeter and check the fuses in the engine bay fuse box for continuity (the fuse box is over on the left side of the engine bay towards the rear). Remove each fuse one at a time, check, and replace. Look for fuses with EFI in the name and check them first.
     
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  3. Bryce Paige

    Bryce Paige Junior Member

    Joined:
    Aug 15, 2021
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    Location:
    Bay Area
    Vehicle:
    2007 Prius
    Model:
    N/A
    Thank you! I gotta say that solution was so easy I passed right by it. It ended up being the most blatant fuse in the whole box haha. Got the car up and running this morning
     
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  4. dolj

    dolj Senior Member

    Joined:
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    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    Glad to help.

    I just need to ask about his:
    Did you use insulation tape to reinsulate any bare wires "rubbed raw" and then attempt to route (and zip tie) the wires so they do not touch any hot parts?

    If you haven't done this you could have the problem (or worse) again, it should be prioritized with the utmost urgency.
     
    #4 dolj, Aug 19, 2021
    Last edited: Aug 20, 2021
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