Gen 2 Actuator ringing or P0011 cam timing? Red Triangle + Brake/VSC

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by actuator_actuating, Jun 11, 2026 at 11:26 PM.

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  1. actuator_actuating

    actuator_actuating New Member

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    2006 Prius
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    Recently bought a 2006 Gen 2 at about 190k miles. Pre-purchase inspection found only ordinary wear: front brakes, tires, P0136 (downstream oxygen sensor circuit: Bank 1, Sensor 2). Had the front brakes done shortly after.

    Since then: I've noticed a short, high-pitched ringing/whirring at startup and intermittently during low-speed braking and pulling away. Brakes feel completely normal - pedal's never stiff, stops fine. Sounds like an old telephone ring or a metal chain. (Found the video below as the closest example. Mine's less severe and without the knocking, but the higher-pitched part is almost dead-on).

    Today while driving the Brake System warning light (circle with !), VSC, and Red Triangle (!) all lit together - no ABS light (the check engine was already on from the P0136 and I'm aware of the TPMS). Image below.

    On the next restart only the Red Triangle remained, while the Brake System and VSC lights were gone and haven't returned since - though the car's only done brief low-speed parking-lot moves for towing since so far, not a real drive.

    A scan showed P0011 (intake cam timing over-advanced, Bank 1) as well as the known P0136. Codes were cleared at the time of the scan, so I don't know whether the brake ECU had any stored C-codes before they were cleared. The ringing continued after clearing.

    My questions:

    Does the actual ringing/whirring/high-pitched buzzing sound itself fit normal Gen 2 actuator operation, or does that particular sound suggest early actuator/booster failure? Does it need to be replaced?

    Could P0011 explain the Red Triangle remaining after the restart, while the temporary Brake System Warning and VSC lights point to a separate intermittent brake-system problem?

    What would be the most useful next diagnostic step now that the original codes were cleared?

    Thank you very much!!!

     
    #1 actuator_actuating, Jun 11, 2026 at 11:26 PM
  2. ChapmanF

    ChapmanF Senior Member

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    The brake pressure pump sounds a little like a joy buzzer or a rattlesnake, and it runs whenever the stored brake fluid pressure needs to be built back up, as it goes down a little each time you use the brakes, and more slowly when you're not. So we like hearing the sound of the pump. It's doing what it's there for.

    Sometimes if the brake actuator is wearing out, you'll end up hearing the sound of the pump but crazy often. That's when to start thinking of it as an issue.
     
    #2 ChapmanF, Jun 12, 2026 at 8:45 AM
  3. Tombukt2

    Tombukt2 Senior Member

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    Can you make that honking noise at the very end of the video or near it middle of it whatever where it sounds like press is bypassing a relief valve . Can you make this happen just stepping on the break if so have someone do that and wen it honks like that be touching brake parts actuator block the thing under resvoir that hold brake fluid . When mine was honking it was that little thing right under the brake res on fender well. On one car bleeding the brakes stopped this noise . I've not changed an actuator for this noise that I know of.
     
    #3 Tombukt2, Jun 12, 2026 at 10:49 AM
  4. ChapmanF

    ChapmanF Senior Member

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    Pretty sure the honking noise is fluid going extra fast past one of the normal valves (not any kind of unusual relief valve) because there is air-bubble space re-expanding as you release the brakes. Honks the valve like a saxophone reed. Stops if you get the air bubbles out.
     
    #4 ChapmanF, Jun 12, 2026 at 11:14 AM
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