2012 Prius w/ 280k miles... high-pitched whining sound? while motionless, idling..?

Discussion in 'Gen 3 Prius Main Forum' started by viciousthinker, Jun 10, 2026 at 12:25 PM.

  1. viciousthinker

    viciousthinker Junior Member

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    hi all, subject pretty much says it all… my 2012 prius, with 280k mileage is making a distinctly high-pitched whining sound while motionless, sitting idling... I tried to determine where it was coming from, ruled out HVAC by turning it off and the whine remains. it sounds like it's coming from either dead center or to drivers side under the hood, it seems to stop altogether when the ICE turns off.

    when I noticed it last night I was putting gas in my car, and it sounded super loud from outside the car... another odd thing I noticed at the same time, I was putting gas in the car with it running, something I have done many, many times in the past... and when I unscrewed the gas cap, and inserted the pump nozzle, there was some kind of suction present? it even emitted a noise that is kind of hard to describe when I first started pumping gas, lol almost like a 'glug-glug-glug' sound that tapered off fairly quickly. maybe this is normal behavior and I just hadn't filled up much w/ the ICE on?

    butthe whining sound is new, for sure... I tried searching for previous posts that mention whining but all I saw had to do with the car being in motion when whining, not just sitting idling....

    any ideas, insight or ridicule guys? cheers all, you guys are the best.
     
    #1 viciousthinker, Jun 10, 2026 at 12:25 PM
    bisco likes this.
  2. ChapmanF

    ChapmanF Senior Member

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    Can you post a recording?
     
    #2 ChapmanF, Jun 10, 2026 at 4:21 PM
  3. BiomedO1

    BiomedO1 Senior Member

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    Well it seems obvious to me; If it only whines with the ICE - ON, something turning with the ICE is screaming - "FIX ME". Driver's side squealing could be the inverter - check the inverter coolant pump.

    Most gas stations around here requires people to turn-off their cars while fueling; that way you don't set-off an EVAP code.
     
    #3 BiomedO1, Jun 10, 2026 at 4:30 PM
  4. rjparker

    rjparker Tu Humilde Sirviente

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    Agree.

    IMG_1766.jpeg

    If it looks like a duck, walks like a duck, and quacks like a whining duck, it’s probably a rotating object on the engine with issues.

    Inverter pump is logical. Or a vacuum leak.

    A mechanic's stethoscope would pinpoint.
     
    #4 rjparker, Jun 10, 2026 at 5:31 PM
  5. ChapmanF

    ChapmanF Senior Member

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    The most commonly asked-about 'whine' under the hood of a gen 3 comes from the throttle body motor and is normal, an acoustic form of the pulse train that positions it. But some of the details the OP has given here might not quite match with that, which is why I asked about posting a recording.
     
    #5 ChapmanF, Jun 10, 2026 at 5:42 PM
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