4th gen Engine swap

Discussion in 'Gen 3 Prius Technical Discussion' started by Ata, Nov 18, 2025.

  1. Ata

    Ata New Member

    Joined:
    Nov 18, 2025
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    Location:
    St louis
    Vehicle:
    2015 Prius
    Model:
    Four
    Swapped the engine with a 4th gen engine
    Now it says hybrid malfunctioning and throws
    Poa40 and poa41 error
    Anybody has any idea whats up with it?
     

    Attached Files:

  2. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
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    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    Looks like the Gear wrench software. . I got a bunch of this changing from federal to JDM gen3 swap . The JDM throttle body didn't seem to be happy and a miserably failing HV battery. Once dealt with . All worked for a short while . Everything's plugged up safety plug in and all that ,?
     
  3. ASRDogman

    ASRDogman Senior Member

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    May 29, 2018
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    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    Everyone has issues when the put the different engine in. If you search prius chat you can find many
    threads about the issues and how to possibly get a fix for them.
     
  4. Mendel Leisk

    Mendel Leisk MMX GEN III

    Joined:
    Oct 17, 2010
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    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    What was the miles, and the reason for doing the swap?
     
  5. Farkhod

    Farkhod Junior Member

    Joined:
    Nov 3, 2024
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    Location:
    Missouri
    Vehicle:
    2008 Prius
    Model:
    Three Touring
    Hi Mendel it’s Frank I did for him swapping engine for now this fault is gone p0a40/p0a41 but we have new issue there is no coolant circulation ( I did several times swapping gen4 to gen 3 but this is first ever times happening with me )
    Vehicle get almost overheating thermostat is not opening I swapped old engine thermostat housing also swapped water pump but something nothing is changed is there could be engine defect? Again all houses lined up connected no leaking coolant but no circulation flowing