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2012 P0300 P0301 P0302 CEL ON

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Marioaz, Dec 30, 2019.

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  1. Eddie25

    Eddie25 Active Member

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    Of course, feel free to take 10 minutes to check the pipe. I refer to cleaning the cooler.
     
    #21 Eddie25, Jan 16, 2020
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Not exactly DIY, but a leak-down test is commonly used. One at a time the cylinders are set to Top Dead Center on the compression stroke, an air hose connected (basically a pressure hose without the valve), a special leak-down guage set is connected, and then compressed air is supplied. The behaviour of the gauges, and just observation, help diagnose what is leaking and where.

    Even without the special gauge set, just doing the above and ovbserving, you can diagnose quite a bit. You're looking for air leakage, and where. For example, if there's bubble in the coolant reservoir, you've got a leak between cylinder coolant passage.

    He has problems with his gauge set here, but still informative:

     
    #22 Mendel Leisk, Jan 17, 2020
  3. Marioaz

    Marioaz Junior Member

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    Thanks much for all your suggestions. They all make sense now. The coolant level is steady, but I did not drive the car much just few miles. It does rattle mostly when is cold started, after the first start seems fine, but the overall milage for short distance seems low. The oil looks clear and steady. It might be small internal leak, but the fact has been registered on 3 cylinders make me nervous.
    Have you every try or use the stop leak like Bar's Head seal if is not much to lose.?
     
    #23 Marioaz, Jan 20, 2020
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    The code p0300 is random misfire, and p0301/p0302 indicates misfire on cylinders 1 and 2. This is becoming classic third gen head gasket failure codes. The head gaskets fail between cylinders 1 and 2. Maybe due to the introduction of EGR gas at the other end, the cylinder 4 end of the intake manifold?

    I wouldn't. You're just getting a short reprieve, and messing up everything the coolant passes through. FWIW, that cr@p can apparently be flushed out with a 50/50 white vinegar/what solution.
     
    #24 Mendel Leisk, Jan 20, 2020
    Grit likes this.
  5. Grit

    Grit Senior Member

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    You’ll lose everything in the seal’s path; it clogs leaks and then regular open passages that needs to be open for flow.
     
    #25 Grit, Jan 20, 2020
  6. Marioaz

    Marioaz Junior Member

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    Thanks much for your feedback. The Bar's Head package will be returned to Amazon warehouse tomorrow. :)
     
    #26 Marioaz, Jan 21, 2020
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