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Check engine light for the first time. P1117

Discussion in 'Gen 2 Prius Technical Discussion' started by MrSteveB, Mar 6, 2014.

  1. MrSteveB

    MrSteveB Member

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    Hey guys, finally got my first check engine light at 108k miles. Pulled my codes with an OBD reader from Oreilley auto parts. P1117 is Coolant temperature sensor circuit, low for coolant heat storage system.
    Coolant heat storage tank outlet temperature sensor.
    Short in temperature sensor circuit
    ECM
    I just wanted to make sure I had the right piece before I buy it. I did check the levels of my coolant and they are perfect, so I'm sure the sensor must be bad.
    I believe it'll just be a water temp sensor. I just want to make sure it's this, and not some random sensor I'm missing.

    Looks like non OEM are pretty cheap online so that's the route I'll take. Any help would be appreciated.
     
    #1 MrSteveB, Mar 6, 2014
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I agree that the temperature sensor at the outlet of the coolant heat recovery canister may have failed. You might use an ohmmeter to measure the resistance across the sensor terminals. The resistance should range from 156K ohms at - 40 degrees F to 79 ohms at 284 degrees F. I assume that the temp of the sensor will actually be in the range from 50 degrees F to 180 degrees F, which shows you that the actual resistance should be well within that range.

    If you find that the sensor resistance is OK, then you may have a short in the wiring harness or the harness connector that plugs into the sensor.

    Should you find that the sensor actually has failed, I would encourage you to buy the correct Toyota part rather than aftermarket.
     
    #2 Patrick Wong, Mar 6, 2014
    MrSteveB likes this.
  3. MrSteveB

    MrSteveB Member

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    I will measure the resistance when I get home. I'm pretty sure this is the piece that needs to be changed, it explains why my car bogs down occasionally when I give it a little more acceleration. Will I find this on my coolant reservoir or more on my radiator?
     
    #3 MrSteveB, Mar 6, 2014
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Neither location. You need to jack up the driver's side front corner of the car, place a jackstand to hold that corner of the car up, and remove the tire. Then remove the fender liner at the front of the fender, to gain access to the coolant heat recovery canister. At that point you should see the sensor at the canister outlet.

    Failure of this sensor would not produce the driveability symptoms that you had described. "Bogs down" might be due to an engine misfire (check the iridium spark plugs), inadequate fuel rail pressure, or clogged fuel injectors. Also check the engine air filter.
     
    #4 Patrick Wong, Mar 6, 2014
  5. MrSteveB

    MrSteveB Member

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    These jobs are never as easy as I had hoped. Plugs and air filter should be good, replaced anout 18,000 miles ago. Air filter should be good too but I'll check it anyways. The symptoms are that occasionally when the gas is about 3/4ths of the way pushed down the car will drop down in rpms to almost idle then rev back up and keep dropping down until I let it go. Otherwise if I push it to the floor it will accelerate on max just fine.
    Patrick, thanks a lot for your help so far.
     
    #5 MrSteveB, Mar 6, 2014
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Very strange.

    You might try disconnecting the 12V battery for a few minutes, then reconnect, to give the ECUs a chance to power down and reset. This sounds like the hybrid vehicle ECU is having trouble deciding how much power to require from the engine ECU.
     
    #6 Patrick Wong, Mar 6, 2014
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