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Post Engine Swap - P0118: Engine Coolant Temperature Circuit High Input

Discussion in 'Gen 3 Prius Technical Discussion' started by Chris Dunbar, Apr 28, 2023.

  1. Chris Dunbar

    Chris Dunbar New Member

    Joined:
    Apr 27, 2023
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    Location:
    New Hampshire - USA
    Vehicle:
    2012 Prius
    Model:
    Two
    Just finished doing an engine replacement. I ran it for 20 minutes or so and ran it up and down the road a half dozen times.
    Engine runs well when cold but very rough when warm which makes sense considering the following errors.
    Water pump runs continuously.
    Does not appear to be overheating or have not blown that gasket yet.
    P0118: Engine Coolant Temperature Circuit High Input
    P3191: Unknown code
    I tested the sensor, continuity appears to be in spec, I think but I'm no expert.
    And I have 5 volts at the sensor wire which I think is correct.
    When the sensor is unplugged completely Water Temp Dummy Light on Dash Illuminates.
    When the sensor is plugged in,the light is not illuminated - this makes me think something in the car can 'see' the sensor.
    Where do I go from here??
    Do I need a 'Tech Tool' better than a OBDII Scanner tool to reset the code?
    I have checked the thermostat,it's ok.
    Thanks so much !
    Chris
     

    Attached Files:

    #1 Chris Dunbar, Apr 28, 2023
  2. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
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    1,359
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    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    If you use your "obd scanner" to look at engine data, what does it show for coolant temperature?

    The Gen3 Prius has TWO coolant temperature sensors. The one you checked is used to monitor function of the exhaust heat exchanger.

    There's another sensor that screws into the cylinder head just underneath the EGR cooler. This is the "main" ECT used to control water pump, cooling fans, and other things. My diagram says it has a pink and a brown wire.

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, May 1, 2023
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