Help troubleshooting unknown sound needed

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by dbogs, Oct 17, 2025 at 10:12 PM.

  1. dbogs

    dbogs New Member

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    Hi Everyone-

    I just upgraded from an ’07 Prius to a 2022 XLE (Gen 4), and when I put the car in reverse I hear a subtle but odd sound I never heard in my older model. It’s a continuous low-level, almost like a throaty hum electrical buzz echoing inside a tube. It’s not loud or intrusive — just noticeable (my 07 doesn’t do that )

    I hear it coming from front way under center of dash, or back of engine compartment when car is put in reverse and continues while backing up. Also hear it a little of it, like 50% loudness, at times going forward very slow, 18mph or less. Anyone else experience this in their Gen 4 Prius? Is it normal — inverter, brake actuator, or something else? My wife thinks it the sound of the electric motor that’s moving the car - maybe- but even if so-- should I be hearing that??

    I just got this car- and I have 7 days to return it. So your input is really needed and greatly appreciated for sure!
     
    #1 dbogs, Oct 17, 2025 at 10:12 PM
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Is it the Vehicle Pedestrian Notification System?
     
    #2 Tideland Prius, Oct 17, 2025 at 11:15 PM
    Tande and BiomedO1 like this.
  3. dbogs

    dbogs New Member

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    OMG- that's it! I feel like an idiot. It's just such an unusual sound and my 07 just beeped . After your response I looked on youtube for posts of the sound and there it was - one person called it "the ridiculous noise". It is an odd sound. I never suspected it would be a warning sound. Thank you!!
     
    #3 dbogs, Oct 18, 2025 at 9:56 AM
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  4. rjparker

    rjparker Tu Humilde Sirviente

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    Exactly. The noise maker to warn people you are moving in ev mode. Recent hybrids are louder than gen2 or 3 which often required you to be in a drive through next to a wall to hear it.
     
    #4 rjparker, Oct 18, 2025 at 11:48 AM
  5. BiomedO1

    BiomedO1 Senior Member

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    Yep; Pedestrian Notification System and internal reverse beeper. Someone who didn't know what they were doing, most likely stuffed or siliconed those speakers/noise generators shut. You can't remove them because that'll trigger the CEL

    When you throw the car into reverse, there should be either a single beep or a consistent warble while in reverse. If it doesn't do that, someone has been messing with it. The OEM settings allows you to reduce the warble to a single beep. Again, somebody, not an authorized OEM tech has been messing with it.
    Ditto with the Pedestrian warning system - speaker in near the car horn. Activates in forward motion below 25-30 mph

    Hope this helps.....
     
    #5 BiomedO1, Oct 18, 2025 at 11:48 AM
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