1. Attachments are working again! Check out this thread for more details and to report any other bugs.

permanent P0102 readiness monitor stuck "incomplete"

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

  1. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    22,812
    14,822
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    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?
     
    Valiant V likes this.
  2. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    3,412
    1,212
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    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 Senior Member

    Joined:
    May 27, 2020
    1,607
    756
    0
    Location:
    California
    Vehicle:
    2010 Prius
    Model:
    IV
  4. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    22,812
    14,822
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    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."
     
    Valiant V and vvillovv like this.
  5. sLick415

    sLick415 Member

    Joined:
    Apr 30, 2012
    214
    55
    0
    Location:
    San Francisco, CA
    Vehicle:
    2012 Prius
    Model:
    Three
    Same issue on my lady's Prius C. 800 miles later, still hasn't cleared itself.
     
  6. jzchen

    jzchen Newbie!

    Joined:
    Apr 9, 2012
    3,292
    1,004
    0
    Location:
    Arcadia, CA
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    Maybe, just may be, related:

     
  7. gromittoo

    gromittoo Active Member

    Joined:
    Mar 9, 2017
    718
    283
    0
    Location:
    philadelphia
    Vehicle:
    2013 Prius v wagon
    Model:
    Two
    I could not resist. Did you pick up your car and shake it a few times?

    I too have the issue, and I think you mentioned it on the the EGR Cleaning Thread I started. I only see it in TS.
     
  8. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    22,812
    14,822
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    I'm looking for a better way. I've got stuff in there that would get discombobulated if I shook it.
     
  9. Elektroingenieur

    Elektroingenieur Senior Member

    Joined:
    Jan 8, 2017
    2,515
    3,248
    9
    Location:
    California
    Vehicle:
    2016 Prius
    Model:
    Three Touring
    The Repair Manual (more info) for model year 2011 gives a different detection condition and confirmation driving pattern for DTC P0102. Perhaps this was actually a mid-year change for which Toyota never updated the 2010 edition of the manual.

    The updated detection condition now depends on engine speed:

    Mass air flow meter sub-assembly voltage is below 0.2 V for 3 seconds
    (1 trip detection logic: Engine speed is less than 4000 rpm)
    (2 trip detection logic: Engine speed is 4000 rpm or more).

    The confirmation driving pattern adds two steps that aren’t in the 2010 version:

    11. During normal driving, increase the vehicle speed to 50 mph (80 km/h) [D].
    12. Depress the accelerator pedal fully to increase the vehicle speed to between 62 and 75 mph (100 and 120 km/h) (engine speed of 4000 rpm or more) and then maintain the speed for at least 5 seconds [E].

    (“[D]” and “[E]” refer to a new figure, showing speed over time.)
     
    Mr. F likes this.
  10. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    22,812
    14,822
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Saaay, now that could mean that after my trip to Anderson the other day ... [hauls out laptop, checks out car] ... woo hoo! All Readiness shows the P0102 monitor is at last complete and normal, and the DTC list shows the permanent code is gone!

    Just hadn't had much occasion to drive like that over the last year.
     
  11. Steelholder

    Steelholder Junior Member

    Joined:
    Oct 25, 2022
    70
    17
    0
    Location:
    Encino
    Vehicle:
    2010 Prius
    Model:
    Three
    Could someone please post all driving pattern steps to get rid of this code, would be much appreciated.
     
  12. Bert41

    Bert41 New Member

    Joined:
    Feb 11, 2024
    1
    0
    0
    Location:
    Texas
    Vehicle:
    2014 Prius
    Model:
    Two
    After my engine grenaded at 92,000 miles, I too had this problem. I put a new engine in, thanks to RagingFit and the GasketMasters on youtube.

    The best way to avoid permanent P0102 readiness monitor stuck "incomplete" is to remember to plug in the MAF sensor and don't leave it unplugged while the Prius is on. I followed the steps posted by Elektroingenieur and the monitor still reported incomplete after a few tries and driving the P101 driving confirmation pattern. You can check if the monitor ran with Techstream by clicking on Powertrain > Engine and ECT> Utility > clicked on All Readiness, typed in P0102, hit next and the monitor shows a status. I think the monitor was still not running for some reason.

    What I did to get the monitor to run again was, I cleared the DTCs. Powered off the car and waited 30 seconds. Disconnected the negative battery terminal for 10 minutes. Connected the battery. Before I followed the attached file with the MAF Low Input Driving Confirmation steps, I also did the ISC Leaning Initialization procedure, which is put the vehicle in maintenance mode and let the coolant warm up to 158F. You should see the ISC value in Techstream change change to completed. This supposedly fixes the Loud Rattle from Hybrid vehicle transmission. I noticed a little difference. I only mention this because it could have affected the P0102 monitor not running, but I doubt it. I then did the MAF Low Input Driving confirmation pattern the same steps posted by Elektroingenieur. Note: I would be uncomfortable doing the steps on a cold engine because of the hard acceleration. The directions say "Depress the accelerator fully". What I did was let the engine be warmed up, idle for a minute, drive up to 50 mph for several seconds, and push the accelerator to the floor **cross your fingers your engine doesn't blow up- I hate this step** and I SET cruise control at 64 mph- a speed that must be between 62 and 75mph. Then I pulled into a parking lot to check if the monitor even completed and in Techstream clicked on Powertrain > Engine and ECT> Utility > clicked on All Readiness, typed in P0102, hit next and the monitor shows COMPLETED! I did another trip or two of the MAF Low Input Driving confirmation steps, powering off the car in between, and did one included universal trip. Reran Health check and the P0102 permanent DTC cleared. Never was a pending or current P0102 present for days/months, this must be true for the permanent DTC to clear.

    If you have a library card or college id some institutions will allow you access to ChiltonLibrary free where a recent version of the Repair manual is. After you login, type in your year make, model and the manual showed up. Google ChiltonLibrary click on Access Through your Library at the bottom of the page.
     
  13. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    22,812
    14,822
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The engine is under computer control at all times, and the computer knows the maximum RPM it will ever ask for. There isn't any driver input you can make that will blow up the engine. A Prius engine blows up because of previous mechanical damage or such severe wear that it was going to go soon anyway.

    If the E0E recall hasn't been applied on your car, a full-throttle acceleration might have some slight risk to your inverter, but that'd be like winning the lottery, plus you get a new one for free.