CEL 1121 strangeness

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Kal Of The Rathi, Jun 2, 2018.

  1. Kal Of The Rathi

    Kal Of The Rathi Junior Member

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    Picked up a 2008 with 180K at a reasonable price. Previous Owner replaced control valve recently.

    However it keeps throwing CEL. Code was originally two including 1121. Bled the air but the radiator bleed wouldn't budge. Replaced it, bleed system. Reset code. Repeated drives give no CEL, car runs fine, ICE is running ~185F.

    However, it does occasionally throw the 1121.
    If I turn the car off when the wait is < 10min CEL on.
    If the wait is an hour+ (not sure the exact cutoff time) no CEL.

    The weird part is I can sit there with IGN-ON for the ten minutes without the ICE running once and it doesn't throw the 1121 for the return drive.

    This is baffling, and quite irritating. Suggestions?
    I am setting up to do drain the coolant and refill via vacuum setup.
     
    #1 Kal Of The Rathi, Jun 2, 2018
  2. bisco

    bisco cookie crumbler

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    there are bleeding directions here if you can find them. try patrick wong.
     
    #2 bisco, Jun 2, 2018
  3. JC91006

    JC91006 Senior Member

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    Did the previous owner show you a receipt for the repair?
     
    #3 JC91006, Jun 2, 2018
    Last edited: Jun 2, 2018
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I do not understand this statement. Do you mean that you could not open the bleed valve located on top of the radiator, which requires a 6 mm hex key to open?

    The engine coolant heat recovery system pump runs upon startup and shutdown. If you leave the Prius READY during a waiting period, then the coolant heat recovery system pump does not need to run.

    My suggestion is that you need to make sure the coolant heat recovery system canister is full of coolant. The best way to do that is to run the CHRS pump manually for 30 seconds at a time. The relay which controls the CHRS pump is located in the little relay box mounted to the cowl, above the engine cylinder head.

    See my post #22 here for info about how to run the CHRS pump.
    Changing engine coolant | Page 2 | PriusChat
     
    #4 Patrick Wong, Jun 3, 2018
    Kal Of The Rathi and SFO like this.
  5. Kal Of The Rathi

    Kal Of The Rathi Junior Member

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    It's shiny new.
     
    #5 Kal Of The Rathi, Jun 4, 2018
  6. Kal Of The Rathi

    Kal Of The Rathi Junior Member

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    I haven't run the pump specifically. I will use your method this afternoon.

    The inner hex key had been rounded out. Wouldn't hold even a short handled key to allow removal. I replaced the plastic part and its o-ring after Dremel-ing off the top (in a failed attempt to make it 10mm wrench sized). Then drilled out the threaded portion and removed the remains.

    Thanks
     
    #6 Kal Of The Rathi, Jun 4, 2018
  7. Kal Of The Rathi

    Kal Of The Rathi Junior Member

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    Update, I drove the car yesterday. A brief run then waiting an hour (appt.) and returned home. Once home I turned off the car and waited 10min then drove it around the neighborhood. Ten minutes seemed to be the triggering time. There was no CEL. I don't have any long trips planned but I will work something into the schedule this weekend.

    Running the pump pulled the coolant level down in the neck of the radiator (where the radiator cap is) down ~1+". Not down to the angle.

    Again, thanks to the chatroom.
     
    #7 Kal Of The Rathi, Jun 7, 2018
  8. JC91006

    JC91006 Senior Member

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    What pump is running that would pulled the coolant down from the radiator neck? If it goes down 1", it doesn't matter. If it's still giving you problems, try changing just the radiator cap. It seems the radiator is full, maybe it's not holding pressure.
     
    #8 JC91006, Jun 7, 2018
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  9. Kal Of The Rathi

    Kal Of The Rathi Junior Member

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    Okay, I'll give that a try. I need to hit Toyota dealer tomorrow and get a second dongle. Wife wants a backup.
     
    #9 Kal Of The Rathi, Jun 7, 2018
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