I desperately need help figuring out what's going on.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by galluccib, Aug 22, 2026 at 10:58 PM.

  1. galluccib

    galluccib New Member

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    Vehicle:
    2012 Prius
    Model:
    Two
    Looking for some help with a 2012 Prius Two that I picked up at an auction. The car has 202k miles, and when starting it, it had a noticeable shake. After pulling the codes, I found P0301 and P0302.

    After doing some digging, I found that it was likely the coils, plugs, or a head gasket issue. I pulled each of the spark plugs and used a scope to check each cylinder for coolant, but I didn't find anything. So, I went ahead and ordered new plugs and coils. I cleared all the codes, and it started right up with no shake.

    Then this is where it gets weird. After shutting the car off, I heard a really odd noise and cannot seem to figure out where it's coming from. It's hard to even describe the noise. Then, after that one stopped, another noise started as well.

    Here are both videos in order.



     
    #1 galluccib, Aug 22, 2026 at 10:58 PM
  2. bisco

    bisco cookie crumbler

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    I don't see any videos. you might need 5 posts, idk. I think you can link to a YouTube maybe
     
    #2 bisco, Aug 24, 2026 at 2:02 PM
  3. PriusCamper

    PriusCamper Senior Member

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    Can you describe the sound? Have you been losing coolant? If your misfire codes were from cylinder 3 & 4 you'd 100% be able to fix it with coils and while you're at it plugs. However your error codes are cylider 1 & 2 and thats where 2010-2015 have head gasket failures. And go ahead and try plugs and coils, but brace yourself for potential bad news. On the bright side folks with little to no skills have successfully done the headgasket job thanks to youtube videos and help from people on here. Also you can get away with driving a Prius with a bad headgasket for a suprisingly long time before the fail... The risk of doing that for too long is destroying the drivetrain dampener or worst of all a bent piston rod if you get so much coolant in the cylinder that it hydro locks.
     
    #3 PriusCamper, Aug 24, 2026 at 3:14 PM
  4. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Did the car have enough coolant in it in the first place?

    Did you do your test with the cooling system pressurized?

    If not, you may not have valid test results.
     
    #4 Leadfoot J. McCoalroller, Aug 24, 2026 at 3:25 PM
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