Loud Rumbling Noise on Startup…

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Sh0, Mar 6, 2025 at 6:08 PM.

  1. Sh0

    Sh0 New Member

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    2008 Prius
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    Hello, I’ve got a 2008 Prius with 190k miles on it that recently started making a loud rumbling noise when I start it up. At first I thought it might be a loose screw causing the cat shield to rattle against the frame on the lower gears but the rumbling stops after a couple of minutes and doesn’t come back until I start it up the next time. Does anyone have an explanation for this? I’ve attached a link to YouTube with a video of the sound.
     
    #1 Sh0, Mar 6, 2025 at 6:08 PM
  2. saneesh8

    saneesh8 Junior Member

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    No codes? Coils and spark plugs good? Is the engine vibrating too much?
     
    #2 saneesh8, Mar 7, 2025 at 12:24 PM
  3. Sh0

    Sh0 New Member

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    No codes other than oil change and tire pressure. I’ll have to check the spark plugs, could it really cause that much noise? The engine does not vibrate at all however…
     
    #3 Sh0, Mar 7, 2025 at 6:40 PM
  4. BiomedO1

    BiomedO1 Senior Member

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    Could be a misfire that your ECU hasn't been able to isolate yet - that's why there's no CEL.
    IMHO; get someone who knows what they're doing to look at it.

    Good Luck....
     
    #4 BiomedO1, Mar 7, 2025 at 8:44 PM
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