2010 - Check Hybrid System (p07E8) Hesitates/Stalls when Accelerating

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by samsonite22, Oct 5, 2021.

  1. samsonite22

    samsonite22 New Member

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    Long-time peruser, first-time poster here. So let me know if I'm posting in the wrong section or anything.

    Great Prius Diagnosers, please help me solve this!

    I have a 2010 Prius. Bought it used and a few days in, the check engine light came on. Then the 'Check Hybrid System' with the other yellow lights. Auto Zone said p0A80 code and Toyota Dealership said the p0A7F (iirc) and wanted to replace the battery.

    Instead of replacing, I found an independent Prius guy to repair the battery. However, he ran Techstream on it and basically said the battery didn't need repairing yet. I forget his exact wording (and am no mechanic), but basically he recommended to keep driving it and reset the error codes when they come on until it shows stronger symptoms.

    So I have. And it still gets great gas mileage. In the past 6ish months since, the 'Check Hybrid System' comes on like once every 2 days and I reset it each time. Keep in mind, I've been driving for Uber with it.

    Yesterday, however, the 'CHS' and lights came on 6 different times during my Uber work. Here are the repeated symptoms:
    • Around 30mph.
    • I'm easing on the gas and it suddenly hesitates a moment, then continues on.
    • If the 'CHS' doesn't come on then, it will the next time.
    • Car increasingly has a rattle like a diesel engine, more often uphill.
    • Occasionally shakes/knocks after hybrid battery is fully charged and high RPM's at stop light
    • My Wal-Mart code reader calls it "p07E8", with "p07EA" underneath it.
    • Possibly unrelated: my AC is taking longer to get cool.
    Basically, it feels similar to when my old car had transmission issues. Except when I press the gas on the Prius, the RPM's do not rev. It's like the Prius is trying to go, it just needs an extra second. Imagine you're breathing normally, but suddenly tense up for a second, then back to breathing. That's what it feels like.

    What makes sense in my non-mechanic mind is something in the gas tank or something clogged.

    Recommendations? Is it okay to keep driving for Uber? Thanks!


    P.S. I've ordered Techstream online in hopes of finding a more specific code.
     
  2. samsonite22

    samsonite22 New Member

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    Oh and it's at 210,000 miles.
     
  3. samsonite22

    samsonite22 New Member

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    And the 12V battery tested as good.
     
  4. rjparker

    rjparker Senior Member

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    The hv battery is dead and not contributing. The engine should be off at a stoplight. In the meantime the engine is dieseling, eg preignition knock because of carbon buildup and no hp from the battery. Keep going and it will strand you and your passengers.
     
  5. samsonite22

    samsonite22 New Member

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    But the HV battery works all the other times. Gas mileage can easily hit 50 mph. Gas engine shuts off most the time I stop. It’s really only a problem on 35mph roads snd then only occasionally. Are you saying the HV battery is dying or dead?
     
  6. rjparker

    rjparker Senior Member

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    If it were me I would take it back to Toyota for an informed diagnostic. Resetting the check hybrid system constantly will only strand you.

    A light is still a light — even though the blind man cannot see it.
     
  7. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Exhaust Gas Recirculation components and EGR passages in the intake manifold ever been cleaned?

    Google search says Mass Air Flow sensor for the code.
     
  8. samsonite22

    samsonite22 New Member

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    Probably won't take it back to the dealer. The guy was nice enough to mention I could find a guy to repair the battery, instead of replacing it. But the only codes and paperwork have that p0A7F code and no more pertinent info.

    Thanks Mendel, I plan on doing some research into those soon, particularly the MAF sensor, since that seems more my speed.

    The next day, the car ran fine. A little "transmission" delay or two, but the code came on only once. While parked, oddly, which is super rare.

    The day after that, I drove 500 miles to New Orleans. Got nearly 60 mpg, driving nearly 60mph. Code only came on once, when I turned off my exit and started hitting the gas at 30mph again.
     
  9. samsonite22

    samsonite22 New Member

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    MAF has been cleaned, no difference.

    Yesterday, I cleaned the EGR valve. It was quite dirty. But on the way home, same little hesitation and code came up around 30mph.
     
  10. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Everything highlighted in this pic has EGR gasses passing through, and is prone to clogging. Did you get it all, including the intake manifold EGR passages?

    upload_2021-11-7_8-21-12.png
     
  11. samsonite22

    samsonite22 New Member

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    I only had time to do the EGR valve, but I'll check the others soon. Would you recommend either of the following videos? Or both?



     
  12. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Yes, both those videos are good; one's the intake manifold cleaning, the other for EGR components. Before jumping in read the link in my signature for "Exhaust Gas Recirculation and...". I note a few strategies (contrary to the video) that eliminate spilling coolant in the process. Also I list tools required, some Repair Manual excerpts.
     
  13. samsonite22

    samsonite22 New Member

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    Thanks for the info. I'll be reading and reviewing and making sure I'm fully ready before I take on that project!

    I should correct myself: I recently cleaned the EGR pipe--not the valve. Slowly learning all the accurate terminology hah...
     
  14. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Funny thing: IIRC Toyota calls what everyone here calls the cooler, the pipe.

    forget what they call the pipe lol.

    so anyway, the popular parlance, starting at the head of the flow:

    EGR cooler
    EGR valve
    EGR pipe
    Intake Manifold

    all of the above have EGR passages, prone to clog with carbon.
     
    Paul E. Highway likes this.
  15. samsonite22

    samsonite22 New Member

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    JUST when ya think you're figuring it out!

    But yeah, I'm gonna pace myself for such a big operation. Probably just master removing the windshield wiper cowl thingamajig first.
     
  16. ChapmanF

    ChapmanF Senior Member

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    I'm sure it's fun talking about the EGR and all, but has any progress been made on the P0A80 and P0A7F yet? Have those codes just gone away?
     
  17. samsonite22

    samsonite22 New Member

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    I just use my Wal-Mart reader still and it still says the 7E8 and 7EA code. Car still runs fine 99% of the time until those same symptoms kick in.

    I will add that my Prius guy talked like it was just one cell (if that’s the right word). Like it was just one small part of the hybrid battery pack that would occasionally misfire or something. That was several months ago.

    The car has returned to its normal ‘CEL’ every other day schedule since the 6-times-in-one-day day.
     

    Attached Files:

  18. samsonite22

    samsonite22 New Member

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    DBF79301-4DD0-4B99-BF5D-994D85ADCB2C.jpeg 22B9E3D2-B0AB-4AD1-A7E2-8C8A6E6AB53F.jpeg DBF79301-4DD0-4B99-BF5D-994D85ADCB2C.jpeg 22B9E3D2-B0AB-4AD1-A7E2-8C8A6E6AB53F.jpeg Welp, good news...I think.

    I feel kinda dumb, but I just realized that my code reader shows more codes beyond that initial 7E8 and 7EA diagnosis. After accidentally clicking a button (it only has 2), it showed, not only the p0A80, but also p0102 and p0113. Which makes sense. Based on my research, it feels like a mass airflow issue. I don’t know why the dealership or Autozone (twice) didn’t find or give me these codes. But I’ll try and upload the pics.

    Now. I cleaned the MAF sensor months ago, which didn’t change anything. So I moved on. But now that I have code confirmation, I’m wondering how do I troubleshoot for a bad MAF sensor or intake air sensors? I have a multimeter but I can’t find a good resource for how to test the Prius MAF sensor. I might just order a cheap one on eBay and install it.


    P.S. for p0A80, I’ve accepted the hybrid battery will need repairing one day, but I’m taking my Prius guy’s advice and waiting until it’s more ready and shows stronger symptoms.
     
  19. samsonite22

    samsonite22 New Member

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    Sorry idk why it posted the 2 pics twice.
     
  20. QuarterMileAAT

    QuarterMileAAT Junior Member

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    IMO, this is a better video for cleaning the intake manifold. Shows where in the intake manifold the EGR ports are. Also, it demonstrates that the coolant lines to the throttle body don't have to be removed. The NutzAboutBoltz video instructs to remove the coolant lines to the throttle body and doesn't address the EGR ports.



    Pretty easy to do. But will take use up around 4-8 cans of brake/carb cleaner, depending on how dirty your intake is. Also, I use this Bluetooth OBD2 reader. Works great with on my '12 Prius Three & my 2000 Ford Ranger XLT. The aps I use are Car Scanner (free, though I paid for it) and Dr. Prius. About the only issue I have with this reader is that it is short and takes a bit of effort to remove.
     
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