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Flashing CEL, running rough, multiple codes

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by The Old Wolf, Aug 30, 2018.

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  1. The Old Wolf

    The Old Wolf Junior Member

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    These are the codes that are showing up:

    P0300 2007 TOYOTA PRIUS - Random Cylinder Misfire Condition
    P0301 2007 TOYOTA PRIUS - Cylinder 1 Misfire Detected
    P0302 2007 TOYOTA PRIUS - Cylinder 2 Misfire Detected
    P0420 2007 TOYOTA PRIUS - Catalyst System Efficiency Below Threshold Bank
    C1241 TOYOTA - Low Battery Positive Voltage
    C1256 - Low Pressure Accumulator.

    I know my cat converter has been on the fritz for some time, the CEL was shining away at me. I replaced the main battery with a rebuild about 7 months ago and have had no problems other than the converter code. Drove to work fine yesterday, but when I started up to drive home, the CEL started flashing and the engine was really rough. As I was driving home I noticed that the anti-skid function lit up a couple of times as well (C1241).

    Anyone have any ideas? Possibly a bad ECM? Input appreciated!
     
    #1 The Old Wolf, Aug 30, 2018
  2. bisco

    bisco cookie crumbler

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    how many miles on her?
     
    #2 bisco, Aug 31, 2018
  3. padroo

    padroo Senior Member

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    Start by having the 12 V battery checked. Prii doesn't like low voltage. How old is your 12 V battery?
     
    #3 padroo, Aug 31, 2018
  4. fotomoto

    fotomoto Senior Member

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    You probably have an oil burner. How many miles? When was the last time you changed the spark plugs?
     
    #4 fotomoto, Aug 31, 2018
  5. The Old Wolf

    The Old Wolf Junior Member

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    224000.
     
    #5 The Old Wolf, Sep 1, 2018
  6. The Old Wolf

    The Old Wolf Junior Member

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    224,000... And never yet. :unsure:

    Mm, probably about two years old if I remember the last time I put one in. But I do remember the symptoms or a little bit different the last two times it needed replacing. Still, probably not a bad idea to check.
     
    #6 The Old Wolf, Sep 1, 2018
    Last edited by a moderator: Sep 1, 2018
  7. yeldogt

    yeldogt Active Member

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    you shod not drive when the light is flashing -- telling you that the engine is running bad enough to send unburned fuel to the cat ... unburned fuel will ignite in the cat and destroy it.
     
    #7 yeldogt, Sep 1, 2018
  8. The Old Wolf

    The Old Wolf Junior Member

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    So, I replaced my spark plugs, put in a new MAF just because, checked my battery voltage (11.2, looks like it's still alive) and reset my codes. Still misfiring like crazy. Gotta be something else. Unless anyone has any other ideas, I guess I need to take the thing in and I don't relish the prospect - I'm afraid the dealership will want $3,000 to fix the problem and the car's not worth that.
     
    #8 The Old Wolf, Sep 6, 2018
  9. yeldogt

    yeldogt Active Member

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    Throwing parts is typically not the answer -- my clogged EGR was making the car run rough. Although I did get a code for the valve
     
    #9 yeldogt, Sep 6, 2018
  10. ericbecky

    ericbecky Hybrid Battery Hero

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    Will also get misfires or rough running from a bad coil pack or fuel injector.

    Label all the coil packs with a marker.

    Move coil pack 1 and 2 to cylinders 3 and 4.
    Do the misfires follow?
     
    #10 ericbecky, Sep 6, 2018
    Last edited: Sep 6, 2018
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  11. jerrymildred

    jerrymildred Senior Member

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    Depending on how you tested it, it lookslike the 12V battery is pretty low (11.2), but I can't see it causing misfires. @ericbecky has a good idea for testing the coils.
     
    #11 jerrymildred, Sep 6, 2018
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  12. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    11.2 volts is terrible.
     
    #12 Mendel Leisk, Sep 7, 2018
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  13. The Old Wolf

    The Old Wolf Junior Member

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    OK, will check the coil packs, and I guess it's time for a new battery once I get the misfire issue fixed. I appreciate those who have taken the time to offer help.
     
    #13 The Old Wolf, Sep 7, 2018
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  14. The Old Wolf

    The Old Wolf Junior Member

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    Turns out it was bad coil packs, all fixed. Will change out the battery when I have time. Thanks again to all who took the time to give input.
     
    #14 The Old Wolf, Sep 13, 2018
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  15. ericbecky

    ericbecky Hybrid Battery Hero

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    Thank you for taking time to follow up.

    Glad the advice was helpful.
     
    #15 ericbecky, Sep 13, 2018
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