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Need Help Diagnosing Coolant Overheat / Leak / Codes

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jonathan St. Vincent, Mar 18, 2023.

  1. Jonathan St. Vincent

    Jonathan St. Vincent Junior Member

    Joined:
    Jul 20, 2018
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    Location:
    Nashville, TN
    Vehicle:
    2007 Prius
    Model:
    Four
    I’ve been quite lucky to have smooth riding for about 40k miles since the last “big” job (inverter coolant pump). The advice here was essential to a smooth replacement (including removing air bubbles). I’m decently handy and have access to tools/etc for the work, however, now I’m stuck with this new problem, and not sure where to begin…

    Vehicle: 2007 Prius (not sure trim level)
    Mileage: ~104,000

    Prior (Relevant) Work:
    • Inverter coolant pump failed and replaced (OEM part via RockAuto) at ~65k miles using PriusChat guidance

    Codes:
    • Confirmed P1121, P1123
    • Pending P1121, P1116

    Symptoms:
    • Check engine light
    • Intermittent (few seconds at a time) triangle of death (ToD)
    • No heat in cabin (on full blast)
    • Leaking coolant (decent puddle), driver side near front, haven’t torn down to locate
    • Can see shiny red reflection (of coolant) dripping when car running on underbody trim when looking down into engine bay between inverter case and inverter coolant pump
    • Low coolant in reservoir near front (black snap cap with built in tiny hose)

    I’m going to guess the best courses of action include don’t drive the car and some sort of tear-down to locate the leak(s). Before I do that, has anyone else experienced this set of symptoms, or could perhaps point me to an existing thread? (I’ve looked around but haven’t located my exact issue described and diagnosed yet.) Thanks!
     
    #1 Jonathan St. Vincent, Mar 18, 2023
  2. Tombukt2

    Tombukt2 Senior Member

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    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    The coolant storage tank is just under the headlight if that's the portion of the driver side of the car you're talking about a few inches behind and above are your inverter coolant hoses and your inverter pump and over to the left of that is one of the fat radiator hoses and a few other 5/8 maybe a tad smaller hoses that puts you in about the middle of the car literally in the middle of the front end literally over to the inverter pump and out towards the very front driver side headlight so it sounds to me like you've got a hose leaking which is 100 something thousand miles seems awfully odd some things rubbing something I mean to have a hole and Toyota heavy duty hoses that are used in the Prius they're pretty good generally at $300,000 mi are just showing a little wear in the rubber so at $100,130 I would expect almost new looking
     
    #2 Tombukt2, Mar 18, 2023
  3. SFO

    SFO Senior Member

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    Vehicle:
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    John has a good post that likely applies : https://carspecmn.com/2004-2009-toyota-prius-no-heat-andor-p1121-p1120-p1122-p1123/
    Here is the workup for DTC P1116 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Repair%20Manual/04pruisr/05/2054m/cip1116.pdf

    Here is the workup for DTC P1121 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Repair%20Manual/04pruisr/05/2054m/cip1121a.pdf

    Here is the workup for DTC P1123 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Repair%20Manual/04pruisr/05/2054m/cip1120a.pdf

    [​IMG]
     
    #3 SFO, Mar 22, 2023
  4. Jonathan St. Vincent

    Jonathan St. Vincent Junior Member

    Joined:
    Jul 20, 2018
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    Location:
    Nashville, TN
    Vehicle:
    2007 Prius
    Model:
    Four
    Thanks @Tombukt2 and @SFO ! After some additional diagnosis, and blind feeling/paper towel for wet spots, it turned out to be a bad coolant control flow valve. Thankfully it’s the same repair I’ve performed previously, but certainly annoying for it to fail after only 50k miles. Went with a genuine Toyota part this round (rather than Rock Auto OEM equivalent), and I should be covered until we hopefully trade up for a 2023 Highlander Hybrid for our growing family.
     
    #4 Jonathan St. Vincent, Apr 1, 2023
    Tombukt2 likes this.
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