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

    Joined:
    Saturday
    3
    0
    0
    Location:
    Queen Creek, AZ
    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

    Joined:
    May 11, 2005
    115,533
    52,925
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    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. galluccib

    galluccib New Member

    Joined:
    Saturday
    3
    0
    0
    Location:
    Queen Creek, AZ
    Vehicle:
    2012 Prius
    Model:
    Two
    Odd on mine it shows them.. Just uploaded both the files.



     
    #3 galluccib, Aug 24, 2026 at 2:36 PM
  4. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    13,479
    5,446
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    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.
     
    #4 PriusCamper, Aug 24, 2026 at 3:14 PM
  5. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    8,294
    7,813
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    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.
     
    #5 Leadfoot J. McCoalroller, Aug 24, 2026 at 3:25 PM
    Brian1954 and CR94 like this.
  6. galluccib

    galluccib New Member

    Joined:
    Saturday
    3
    0
    0
    Location:
    Queen Creek, AZ
    Vehicle:
    2012 Prius
    Model:
    Two
    The noise is like blowing through a straw and makes that whistle sound.

    I watched the coolant and never lost any plus as I said I pulled the plugs and used a scope to check each of the cylinders to see if there was anything in there and every time it was dry. After replacing all four plugs and coils starts right up with zero issues and no codes have come back. Everything seems to be working okay and AC is blowing pretty cold for being in AZ temps.

    Only other thing I've noticed is when driving at around 45 it should like a lifter or valve is sticking. Hard to test when sitting still because I can't get the RPM up high enough to reproduce.

    I have the Autel MK808Z scanner and going to see if there is something in there I can test the RPM with,plus I picked up the Toyota VXDIAG VCX Nano adapter and Techstream software.
     
    #6 galluccib, Aug 24, 2026 at 4:31 PM
(You must log in or sign up to post here.)