Had p1116 and p1121 replaced coolant flow control valve and still have p1121 and no heat.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Djsun1, Jul 8, 2026 at 6:12 PM.

  1. Djsun1

    Djsun1 Junior Member

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    Like title says I had both p1116 and p1121 codes. I replaced the coolant flow control valve with an OEM unit. Now I only get the 1 code, p1121. The heat is blowing ambient air, otherwise the car runs well.
    Not sure if this matters but when I cold start it 1st thing in the morning, I get a 3-5 second buzz-werr sound right after starting. Once the car warms up and I shut it down and start it up there is no sound.

    What else can I do to troubleshoot? Could it be a bad pump? How can I test for that?
     
    #1 Djsun1, Jul 8, 2026 at 6:12 PM
  2. JC91006

    JC91006 Senior Member

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    Check your coolant level in the radiator and make sure it’sfull
     
    #2 JC91006, Jul 8, 2026 at 11:02 PM
    Brian1954 likes this.
  3. 6079smithw

    6079smithw Junior Member

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    What JC91006 said, plus did you bleed the heater loop using the ammeter routine after you replaced the valve ? Doesn't take much air in the heater core to make it quit. The bleed routine will also verify the electric pump is working. BTDT Good luck!
     
    #3 6079smithw, Jul 9, 2026 at 1:39 AM
  4. Djsun1

    Djsun1 Junior Member

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    I did bleed the system and put in the same amount of new fluid as I collected of used fluid that came out during the valve swap. I did not do the thing with the relays and the multimeter. Just opened the valve and fed in new fluid while it was running.
     
    #4 Djsun1, Jul 9, 2026 at 2:05 PM
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