replaced Coolant Control Valve+ Inverter Pump getting code again

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Roundgunner, Feb 2, 2025.

  1. Roundgunner

    Roundgunner Junior Member

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    My 09 175K started giving the CEL in September. I pulled it off the scanner and it was 1121. Read up a little and got the parts and did the install early October. PIB for someone with big hands and small patients ;-). I replaced the coolant, bled out the air and it has been great since.

    Last week I was 100 miles from home and the CEL came on again. I was sick as I have been in many years so I didn't look at it until today. Coolant reservoir levels are both good. I didn't notice when it came on but I know I was sick so I wasn't running it fast and hard like normal.

    I searched here and saw a couple things as a maybe. I didn't replace the radiator cap but I will now. I also read about people burping the coolant storage tank. I didn't do that, is it possible to have that give me a problem after at least a couple thousand miles and would it show a drop in the level?

    Any thoughts and help would be appreciated.
     
    #1 Roundgunner, Feb 2, 2025
  2. dolj

    dolj Senior Member

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    One thought I had was, what was the code when you rescanned the car? Or did you assume it was again a P1121?

    Incidentally, DTCs are 5 characters (on a Gen 2) so please include the letter at the start. The valid letters are P, B, C, and U.
     
    #2 dolj, Feb 3, 2025
  3. ChapmanF

    ChapmanF Senior Member

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    Those are the valid letters at the start. :) The last three are also allowed to be letters; those can be A, B, C, D, E, or F.
     
    #3 ChapmanF, Feb 3, 2025
  4. Roundgunner

    Roundgunner Junior Member

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    I did a scan. It is the same code as before.
     

    Attached Files:

    #4 Roundgunner, Feb 3, 2025
  5. BiomedO1

    BiomedO1 Senior Member

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    That's a pretty specific error code and usually the coolant control valve. There's an issue with counterfeit parts, so that valve may have failed again. Also look for wiring harness issues (ie. rodents chewing on your wires) and corrosion in and around your wire connectors - preventing the signal from getting to the ECU. Other things to look for is dirty coolant, if stuff is floating around in your coolant, it can jam the valves as it actuates - resulting in that error.

    Hope this helps....
     
    #5 BiomedO1, Feb 3, 2025
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  6. Roundgunner

    Roundgunner Junior Member

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    I will inspect the wires closely. I did spend double the money on Genuine Toyota but yeah, it's amazing how the Chinese can make anything look right.
    I will also send a message off to the seller and see what he has to say.

    Thank you for the reply 20241006_152124.jpg
     
    #6 Roundgunner, Feb 3, 2025
  7. BiomedO1

    BiomedO1 Senior Member

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    Sorry; that looks like the inverter coolant pump - not the coolant control valve. Wrong picture or is it just the angle of the photo? Attached is a how to:

    Coolant control valve is next to that and below. This takes care of the ICE (internal combustion engine) portion of the car.
    The inverter coolant pump takes care of the EV cooling portion of the car. Two separate and distinct cooling systems.
     
    #7 BiomedO1, Feb 3, 2025
    Last edited: Feb 3, 2025
  8. Roundgunner

    Roundgunner Junior Member

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    I replaced both at the same time. I take photos as I go when taking things apart incase I forget what I did. My memory sucks.
     
    #8 Roundgunner, Feb 3, 2025
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  9. MAX2

    MAX2 Active Member

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    This problem code is not critical.
    It indicates that the three-way switching valve used with the coolant thermos system is clogged. It does not affect the movement of the car.
    Often the potentiometer in the valve wears out and it starts showing the weather on Mars.
    See the manual for checking the causes of this problematic error.

    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
     
    #9 MAX2, Feb 4, 2025
  10. ChapmanF

    ChapmanF Senior Member

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    When the position sensor starts reporting bogus information, the car isn't able to move the valve to the right positions. In some positions of the valve there will be no cabin heat, so depending on the OP's location and the time of year, a problem with the valve can be a nuisance.
     
    #10 ChapmanF, Feb 4, 2025
  11. MAX2

    MAX2 Active Member

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    Connect two hoses (Cylinder Head, Water Pump for Air Conditioner) with a tube, and plug the third hose (Coolant Heat Storage Tank).
    All that remains is the yellow icon on the instrument panel.
     
    #11 MAX2, Feb 4, 2025
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