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2015 Prius P0138 Code Fix?

Discussion in 'Gen 3 Prius Technical Discussion' started by bear15, Jul 14, 2020.

  1. bear15

    bear15 Member

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    We have 55k on our 2015 Prius and today we received the P0138 Code. I cleared the code 3 times and the code keeps coming back on. Does anyone know of an easy fix we can try?

    Thanks for any ideas etc. . . .
     
    #1 bear15, Jul 14, 2020
  2. Vman455

    Vman455 Senior Member

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    The code is going to keep coming back until you replace one or both of the O2 sensors.

    P0138 is the rear sensor specifically, reading high voltage. That could be because the rear sensor itself is faulty, or because the upstream sensor is faulty and the engine is running rich. Have you noticed a change in fuel economy recently?
     
    #2 Vman455, Jul 15, 2020
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  3. bisco

    bisco cookie crumbler

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    strange at 55k, what is the cars history?
     
    #3 bisco, Jul 15, 2020
  4. bear15

    bear15 Member

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    I have own the car since new, completed all schedule maintenance etc., and the car has been (and is) running great with MPG in the low 60's. My last trip was 71.1 mpg over 27 miles.

    I am also shocked that the rear sensor or front air/fuel ratio oxygen sensor could be bad at just 55K. This will be the first repair on this vehicle to date other than regular maintenance.

    I wish there was something else I could try first. . . . . . .. ..


     
    #4 bear15, Jul 15, 2020
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  5. bisco

    bisco cookie crumbler

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    what are you reading the codes with?
     
    #5 bisco, Jul 15, 2020
  6. Vman455

    Vman455 Senior Member

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    My guess is rear sensor then; they're around $100. Little things like this can happen on any car; a wire rubs somewhere, wearing away the insulation, and it shorts to the metal body or another component, for instance.
     
    #6 Vman455, Jul 15, 2020
  7. bear15

    bear15 Member

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    Thanks for the information.

    I wish there was something else I could try first. . . . . . .. ..

     
    #7 bear15, Jul 16, 2020
  8. bear15

    bear15 Member

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    Just a quick follow-up question. Where did you find this sensor for $100? The cheapest OEM I found was $180 plus tax and shipping. Thanks!

     
    #8 bear15, Jul 16, 2020
  9. bear15

    bear15 Member

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    Fixed: The problem was rear sensor wire chewed by a rodent of some kind and we replaced the sensor.

     
    #9 bear15, Jul 18, 2020
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