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"P1121" Check Engine Light coming on and off

Discussion in 'Gen 2 Prius Main Forum' started by priusn00b, Apr 14, 2014.

  1. priusn00b

    priusn00b New Member

    Joined:
    Apr 14, 2014
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    Location:
    Oklahoma City, Oklahoma
    Vehicle:
    2007 Prius
    Model:
    N/A
    I've recent purchased a 2007 Prius and it's constantly triggering Check Engine Light (CEL) on and off; The CEL doesn't stay on for more than 24 hours. I've scanned the code and it turns out to be "P1121" which seems to be the common read for 2nd generation Prius. I really like the car and want to "baby" it yet the tricky part is that the CEL doesn't stay on. I drove it for more than 500 miles and the vehicle rides perfectly fine with 50 MPG. I was wondering if I should fix the coolant valve right away or wait until I sense more, actual problems.
     
    #1 priusn00b, Apr 14, 2014
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Mar 8, 2008
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    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    1. Check the engine coolant level in the overflow container as well as the radiator itself (must remove the large black plastic cover over the radiator for access to the radiator cap.)
    2. If the coolant level is full in both places, then the engine coolant valve needs to be replaced. If coolant is low, that may have been the reason for the DTC being logged.
    3. Depending upon the position in which the engine coolant valve is stuck, you may notice poor cabin heater performance or the engine warmup will be slightly longer than normal, which has mpg and emissions implications.

    Given the above, it's up to you and your standards of vehicle maintenance to decide when that work should be performed.
     
    #2 Patrick Wong, Apr 14, 2014
    dorunron likes this.
  3. dorunron

    dorunron Senior Member

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    Vehicle:
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    Model:
    Three
    #3 dorunron, Apr 14, 2014
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