engine light on code p1121/blowing cold air

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Maeve G, Feb 20, 2024.

  1. Maeve G

    Maeve G New Member

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    My check engine light came on and I took it into a shop where they said it was coming up as p1121 and I needed to replace the coolant control valve. They turned off the check engine light and it didn't come back so I haven't gotten that done yet but in the last day the heat has started blowing cold air. I know the two can be related but the light hasn't come back on so I'm worried it could be something else, should I take it back in to have the coolant control valve replaced?
     
    #1 Maeve G, Feb 20, 2024
  2. JC91006

    JC91006 Senior Member

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    The problem is the coolant valve, replace that and everything will work perfectly again
     
    #2 JC91006, Feb 20, 2024
  3. nolotank

    nolotank Junior Member

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    One of the coolant control valve's jobs is to control the flow of coolant for cabin heat. The combination of P1121 and no heat suggests that the valve is stuck in a position where there is no flow to the heater core. The light can be finicky, I had it on and off for a long time when my valve was bad. I agree with JC that replacing the valve will likely fix all issues mentioned here.
     
    #3 nolotank, Feb 20, 2024
  4. ChapmanF

    ChapmanF Senior Member

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    That valve hasn't really got a job to "control the flow of coolant for cabin heat"; it just happens to be in that coolant path and when it switches over to move coolant through the thermos, you don't get cabin heat then (or ever, if the valve gets stuck that way).

    At all other times, the valve should be giving full flow to the cabin heater, when it's working right. It doesn't "control" that flow. The amount of heat you get in the cabin is controlled by air vanes that direct air either through or around the heater core.
     
    #4 ChapmanF, Feb 21, 2024
  5. mr_guy_mann

    mr_guy_mann Senior Member

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    +1 to the other posts.

    That said, you might want to check the coolant level in the radiator (when the engine is cold).

    A fault coolant 3-way valve can affect flow through the heater core. Low coolant can also cause problems.

    Posted via the PriusChat mobile app.
     
    #5 mr_guy_mann, Feb 22, 2024
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