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Gen 2 Prius ICE Coolant Problem

Discussion in 'Gen 2 Prius Main Forum' started by John Hry, Mar 24, 2021.

  1. John Hry

    John Hry Junior Member

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    2008 Prius
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    ----USA----
    The last few days I have been trying to figure out a issue with my 2nd gen Prius when trying to clear all of the air bubbles out of the system. It all started when I had the check engine light on with the code P1121 which is the coolant control valve so I decided to replace it with one from a pull apart yard I went to. I drained all of the coolant and replaced the control valve and started filling it all back up with coolant just like as seen in this video
    . I then put the car into diagnostic mode and the coolant was flowing and air bubbles were getting out of the system. I Then opened the bleeder valve too much and coolant was leaking from the bleeder valve so turned off the engine. I then jacked up the passenger side of the car and continued to try and use the coolant heater storage pump to try and pump the coolant through the system so it could remove some air bubbles and I could try and run the car again with the same process. This time however the coolant did not get sucked down through the funnel and just stayed at the same level. The coolant heater storage pump was still working as I could still hear it. I thought it might just be a bad coolant control valve as one of them might have closed up so I went and got a OEM part from the Toyota dealership and installed that. Same thing happened and no coolant was being sucked through the funnel. I then went to a pull apart yard and got a coolant heat storage pump and the coolant heat storage tank as well and replaced that on my Prius too just to see if it was the pump that was bad. Still had the same problem where the coolant wouldn't get sucked through the funnel and could clearly hear the pump running when jumped. I decided to try and put as much coolant into the system as I could and put the car into diagnostic mode to get rid of the rest of the air bubbles by running the car. The heat was on and coming out hot, however no bubbles were rising out of the funnel as well and it seemed coolant was not circulating. I felt the hose closest to the drivers door by the radiator and that one was beginning to get hot, however the hose closer to the passenger side was not. The coolant is not flowing and I'm not sure what is going wrong in this situation. Any help would be appreciated
     
  2. John Hry

    John Hry Junior Member

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  3. John Hry

    John Hry Junior Member

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    I'd also like to include that when running the engine hot air comes out of the fan when the air is on HI and still continues to blow hot even after the ICE has stopped running. The codes I have now are P1121 (Coolant Flow Control Valve Position Sensor Circuit Stuck) P1116 (Coolant Temperature Sensor Circuit Stack For Coolant Heat Storage System) and P1122 (Coolant Flow Control Valve Position Sensor Circuit Low).
     
  4. dolj

    dolj Senior Member

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    Your hot heat is because of the P1211.

    For these codes, you need to investigate and find the root cause of why the coolant control valve is stuck and the CHRS (coolant heat recovery system) is flagging an error. It could be the connectors are making a bad connection, a break in a wire or other wiring problem, or the temp sensor or the three-way coolant control valve themselves are the problem areas.

    Fix these problems and your car will work as new.
     
    #4 dolj, Mar 25, 2021
    Last edited by a moderator: Mar 26, 2021
    SFO likes this.
  5. John Hry

    John Hry Junior Member

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    Thanks I'll look more into this tomorrow. I think the connectors are fine as I did not see any corrosion or anything out of the ordinary when installing the new parts. I'm thinking the heater core pump is bad however and the other codes haven't had time to clear as there is still air in the system.
     
  6. PaulDM

    PaulDM Active Member

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    I know this seems like a noob question but have you added coolant to BOTH coolant tanks. The second one being next to the radiator fan?
     
  7. John Hry

    John Hry Junior Member

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    Theres two separate cooling systems (one for the inverter and one for the ICE). The Inverter cooling system was never drained so I only had to add coolant to the ICE cooling system just as seen in the video.
     
  8. John Hry

    John Hry Junior Member

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    *Update* The cooling system was not flowing as the coolant heat storage tank had sucked in some air as I turned off the engine initially. I just had to run the pump a bunch more to get it to clear everything out. The car has no check engine lights anymore and works great.
     
    w2co likes this.
  9. w2co

    w2co Member

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    Keep in mind the coolant heat storage pump only runs after you shut down and the water in the tank is cooler than the coolant in the head.. So it's only used at shut down, not while the car is running.