permanent P0102 readiness monitor stuck "incomplete"

Discussion in 'Gen 3 Prius Technical Discussion' started by ChapmanF, Mar 22, 2021.

  1. ChapmanF

    ChapmanF Senior Member

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    My 2010's ECM has remembered a 'permanent' P0102 for months now, ever since one time I briefly had the MAF sensor unplugged.

    Of course that was easily fixed by plugging it back in. There wasn't anything wrong with the sensor to begin with; having it unplugged was what set that code the only time. The code has never been logged again as a pending, current, or historic code, not even in the extra-sensitive 'check mode'. It only lingers on in the 'permanent' column.

    There is no 'code clear' for codes in the permanent column. They only go away after the right number of drives all achieve the "normal" judgment in the All Readiness utility query for that code. For each code, there's a Confirmation Driving Pattern in the manual that is supposed to be enough to get to "normal" judgment for that code. (If a problem still exists, it gets an "abnormal" judgment. If for some reason not all the enabling conditions for making the judgment were met, it stays "incomplete".)

    After yesterday, because of water pump experiments, I also had a permanent water pump code. This evening I made that one go away by looking up the confirmation driving pattern in the manual, and doing that, and then doing a Universal Trip, and the next time I started the car, the permanent water pump code was gone. Just the way it's supposed to work.

    But this permanent P0102 has never gone away. The All Readiness utility query for it always shows "incomplete", as though some enabling condition for making the judgment is never being met, so it can never decide if the problem's fixed or not.

    What's most weird is this code has about the simplest imaginable confirmation drive. The P0102 code means that the MAF sensor was read as under 0.2 volts. The confirmation driving pattern is every bit of: start the engine and let it idle for five seconds. That's it. If the ECM sees that the voltage isn't under 0.2, that's supposed to earn a normal judgment. In five seconds flat.

    conf.png

    And in the section where the manual lists preconditions, other things that have to be satisfied before the judgment can be rendered on this code ... well, there aren't any.

    enb.png

    And yet, in multiple drives, way beyond five seconds of idling, hitting all the conditions needed for all the other monitors to be complete, the judgment for this one code is just staying "incomplete" forever.

    It makes me wonder if really there is some odd enabling condition for this code's monitor and they forgot to mention it in the manual. Anybody know what it is?
     
  2. vvillovv

    vvillovv Senior Member

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    No bulletproof solution here. My first time reading about this issue. Looks like some get lucky and some don't.
    I'm familiar with a few relearn procedures, but not the P0102. Looking in other threads (at the bottom of this page) Reset "permanent" p0102 , 2013 P0A80 error "permanent" and a couple others here at Priuschat
    I read some notice a 600 mile estimate before the Permanent - clears for them and others appear to never get it cleared.
    Thinking about why the ECU is not getting the info it needs to clear 102 takes me down the proverbial rabbit hole. trim is off, ECU looking for X in Y and not getting Z, VVT, Tech Trix, EVAP / canister / valve, etc.

    Have you pulled the MAF plug again or removed the MAF sensor for inspection,
    almost misspelled MAF as MAP. Don't know what I was thinking as I typed that. :coffee:

    l
    V

    [​IMG]
    Ratchets And Wrenches
    ->> How to Test a MAF or MAP Sensor With a Multimeter - Plus an Operations Guide


     
    #2 vvillovv, Mar 22, 2021
    Last edited: Mar 22, 2021
  3. AzusaPrius

    AzusaPrius Active Member

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  4. ChapmanF

    ChapmanF Senior Member

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    I was at first concerned about that "at the same time" part, because in Techstream the help that pops up for a 'permanent' code says that all permanent codes get cleared at once, and only when all of them have been judged normal the right number of times.

    I was afraid that meant as long as this P0102 judgment stayed 'incomplete', no other permanent code would go away ever, and my ECM would just become an etch-a-sketch of every code I'd ever had with no way to get rid of them.

    But the section in the manual about permanent codes does not say that about them all going away together. And that isn't what happened. My pump permanent code did go away last night, just after driving the confirmation pattern and the universal trip, just the way it's supposed to.

    So I'm back to just the permanent P0102. There's never a current problem reported with the MAF, the engine is running in closed loop and the MAF values are fine. The judgment never completes and says abnormal. It just never completes.

    It really seems as if either the enabling conditions or the confirmation pattern must be wrong in the manual for that code. I'm hoping someone has run into it before and knows "oh, yeah, the manual left out that you have to do X."
     
    vvillovv likes this.
  5. sLick415

    sLick415 Member

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    Same issue on my lady's Prius C. 800 miles later, still hasn't cleared itself.
     
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