bad clunking sound when ICE turns on under low to moderate acceleration

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by JellyDoughnut, Apr 8, 2026 at 12:16 PM.

  1. JellyDoughnut

    JellyDoughnut New Member

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    Hey everyone,
    I've owned my prius for about 5-6 years now and haven't really had a single problem with it until now. Under low to moderate acceleration it makes a sort of repetitive clunking sound and can feel the clunk as well. It goes away in high rpm and electric only.

    I headed to the forums and google and everything pointed towards EGR, so I took that whole thing apart, cleaned everything like all the videos showed. Got the cooler, pipe, valve, and intake all cleaned up but they weren't really that bad like all the videos showed. I could still blow through them perfectly fine. Replaced the PCV valve recently as well. Didn't change at all.

    So now I'm leaning towards a transmission problem, maybe just low on fluid? or the damper plate between the engine and transmission. Any ideas on what else it could be? Or anyway to inspect those parts to see if it's the problem? I heard there may be an inspection port for the damper plate?

    The only code it's throwing, is the P2195 which has been on and off for th entire time I've owned it. Replaced the o2 sensor and didn't really change anything.

    Any help would be appreciated.
     
    #1 JellyDoughnut, Apr 8, 2026 at 12:16 PM
  2. BiomedO1

    BiomedO1 Senior Member

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    I'm not surprised; don't know how a "clunk" can be caused by your EGR? That would have more to do with your P2195 code, though that would also be a stretch.

    Low ATF shouldn't cause that either, if it did - your transmission isn't long for this world and it would be doing that in EV mode too. IMHO; ATF should be changed every 100K miles anyways. It's probably black as tar by now.
    My money would be on the damper plate, motor mount, or a misdiagnosed CV axle joint; based on the description above. You can remove your bell housing inspection plate to look for debris, bits and pieces of the damping springs.

    Good Luck....
     
    #2 BiomedO1, Apr 8, 2026 at 4:36 PM
  3. CR94

    CR94 Senior Member

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    Mileage?
    Is the "clunking" worse during turns?
     
    #3 CR94, Apr 9, 2026 at 12:34 AM
  4. JellyDoughnut

    JellyDoughnut New Member

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    Cars at 240k miles. engine was replaced around 190k with another lower mileage motor.
    No clunk doesn't get better or worse during turns
     
    #4 JellyDoughnut, Apr 9, 2026 at 1:28 AM
  5. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Second “mileage?”

    Engine coolant level stable in the reservoir?
     
    #5 Mendel Leisk, Apr 9, 2026 at 7:39 AM
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