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Check engine light came on this morning-P0101

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by H00s13r, Jun 1, 2020.

  1. H00s13r

    H00s13r Member

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    Hey guys;
    So I recently did the entire EGR/manifold/TB cleaning, new PCV valve, new air filter, new OCC install (Link to original thread) and for a couple of days( we used the car about 35 miles) has been fine-no problems or codes. So this morning when we went out do do a couple of errands, the check engine light came on shortly after we left. Up to this point I never had a check engine light-even before I did all the work. I checked with my cheapo OBDII reader and came up with P0101. I took it to autozone on the way home this morning and they got the same code. I double checked all connections and they look good. Does anyone have any idea of why now I am getting this code? Thanks in advance for all of your help.
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Well the code says MAF sensor; it's for sure plugged in (round back of the air filter box lid)? Did you do anything to it, other than disconnect it to pull off the air box, say clean it?
     
  3. H00s13r

    H00s13r Member

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    Hey Mendel;
    Yeah I double checked and it is connected. I never cleaned it. When I took out the throttle body I did take off the one on there and gently wiped it with a rag to get the oil/crap off, but I didnt use any cleaners on it. I double checked and that one is connected as well.
     
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  4. ASRDogman

    ASRDogman Senior Member

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    Did you remove the maf sensor before cleaning the intake manifold?
    Did you spray it with brake cleaner or carb cleaner? Or whatever you cleaned the manifold with?
    If you did, you may have ruined it.
    You can remove it, and clean it with maf cleaner, or Alcohol and hope it saves it.
    It can't hurt it anymore if you cleaned it with anything else.
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Light "might" go away with a few more startups, say 4~5. If it was just a temporary communication loss.
     
  6. H00s13r

    H00s13r Member

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    Yes I took it along with that other part off so the manifold had nothing connected to it before cleaning anything. I knew not to spray anything on that sensor, but since I didnt have any MAF cleaner spray, I just gently wiped as much of the oil and debris off the end that went into the manifold, then using an alcohol wipe I gently wiped it and then stored it in a box so it wouldn't get damaged. The one on the top of the airbox, I never removed. I did clean the airbox parts off, but again I made sure not to spray anything directly on the top part of the airbox since that sensor was in there. I just cleaned the top of the airbox by hand with a rag and didn't touch that sensor. Should I try removing it and gently cleaning it? Again I have no MAF sensor cleaner, I could just gently wipe with an alcohol wipe.
     
  7. H00s13r

    H00s13r Member

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    I could see that if it was on initially, but it was never on before I did all the work (actually never had a check engine light on ever-this is first time), and for a short while (35miles approx) after I completed the work. I did clear the code with my reader so I can see if it comes back on within the next 30 miles again.
     
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    You're maybe meaning the MAP sensor (Manifold Absolute Pressure) sensor, the one just below the throttle body, around 3 o'clock?

    The MAF sensor (Mass Air Flow), the one indicated by the code, is 'round back of the air box lid.
     
  9. H00s13r

    H00s13r Member

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    Correct-the one on top of the airbox lid (MAF) I never touched.
    The one on bottom below TB and connected to Manifold (MAP) I gently cleaned with alcohol wipe prior to doing all the work. It sat in a box until it was time to put all back together. I reinstalled it onto manifold when I put everything back together.
     
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  10. H00s13r

    H00s13r Member

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    So yesterday I reset the code and then went out this morning. Didn't even get a mile from my house and the damn check engine light came back on. Got home and its same code. I bought some MAF sensor cleaner spray at menards while I was out. I will take off air box, and spray both the MAF and MAP sensors, let them dry and put them back. If that doesn't work, does anyone else have any ideas of what I should do? Should I buy new MAF and MAP sensors? Not sure how much they cost. Anyone have any other ideas I am all ears at this point.
     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    They're pricey, around $250 USD apiece. Yeah...

    There's got to be a clue, in that the code showed up hot-on-the-heels of your EGR clean out.
     
  12. H00s13r

    H00s13r Member

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    ouch. **** that is expensive. I don't know what else it could be. I double checked and I reconnected everything. I don't see anything not connected. The car is starting and running much better than before I did all of this. I have checked the OCC and so far I don't see anything in there. I have only driven the car less than 100 miles since I did all of this work. It is crazy hot out today (over 90) so I am staying inside. Tomorrow morning I will pull out the MAF and map sensors for the spray cleaning. I will also double check everything again since I will have the airbox out and make sure all is connected. When I did all of this I did open up that EGR valve assembly to check that the plunger and spring moved freely. I am pretty sure I put it all back together okay. Could that have something to do with it?
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    @ChapmanF ?
     
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    And car is running good. That's doubly puzzling. Hate to say this, but dealership? Don't rush in, think on it more, but seems like some sorta communication-only issue? Maybe.
     
  15. pjksr02

    pjksr02 Active Member

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    I'm seeing that P101 (actually P101D) refers to the A/F ratio sensor in the repair manual (anyone else see that?).

    P101D
    The heater current is higher than the specified value while the heater is not operating (1 trip detection logic).

    The manual says the trouble area is the ECM. (not sure I'd agree at this point).

    Maybe you bumped the A/F ratio sensor wiring harness when you did your cleaning?
     
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    According to Mr Google, but...: when I start browsing my repair manual excerpts, see mention of EGR valve assembly, in the attached. Maybe EGR valve reassemble not correct:

    Hopefully @ChapmanF will have ideas.
     

    Attached Files:

  17. H00s13r

    H00s13r Member

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    Can you show me picture of area or part you are referring to?
     
  18. H00s13r

    H00s13r Member

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    So maybe when I opened up the EGR valve assembly to check that it wasnt stuck, I didnt put it back exactly correct? Do you or anyone have a video or diagram showing how it should be put together? I mean when I popped the back cap off, I spun off the magnet to find a free moving larger spring over a fixed smaller spring on the valve. I could push that in and it would pop back out freely. I then put large spring back on, spun magnet back on until it was snug, then put the black cap back on with the 2 screws. The black cap only goes on one way so that the electrical connector is at the top. I don't what else I could have done wrong.
     
  19. Mendel Leisk

    Mendel Leisk Senior Member

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    I've never taken it apart (cleaned without taking off the cap), but that seems a "smoking gun". Besides chapmanF, @Raytheeagle ?
     
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  20. pjksr02

    pjksr02 Active Member

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    Thanks for posting that, Mendel. My RM is for the PiP, so might be different(?). The trouble areas listed include just about everything that Hoosier worked on, including maybe the PCV hose!

    Hoosier, from your original thread, it looks like you re-confirmed everything is back together, and that you used new gaskets on the IM and with the EGR system. My first thought was a bad seal around the IM.

    Have you tried putting the original tubing back on the PCV loop, leaving the OCC out of the equation?

    I'm seeing the MAF at $102 at McGeorge Toyota.

    Want my old EGR valve? I replaced it when I did my EGR cleaning.
     
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