Dreaded P0A80 Code - Car Running / Charging Good.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by PriuSocal, Jan 25, 2026.

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  1. ChapmanF

    ChapmanF Senior Member

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    I can see this conversation happening if we were talking theology and you belonged to one of the denominations believing the Bible is completely inerrant in every word.

    But the Repair Manual is a book we know was written by mortals, and edited and translated by mortals, and does have rare, occasional mistakes.

    So if you were a theologian and you noticed two things in the Book didn't seem to make sense together, yes, you would have to bend over backward and say the only possible explanations must somehow fit "to the T" with both parts 'cause you can't allow there could have been a mistake.

    But the Repair Manual doesn't require that treatment. It has very few mistakes (really amazingly few, given its sheer size and the complexity of translating technical info from Japanese to English). But I've found a few over the years, and others have too, and Toyota does have a process in place for accepting reports of errata and fixing them in the online version. I know they do that 'cause they've accepted at least one from me.

    So, first off, if you haven't checked yet what the current, online version says at that spot, there's a very good chance that what we're still going on about is something that may have been clarified or fixed years ago. (I had a permanent P0102 for, like, a year, that I couldn't clear because I was looking at a 2010 Repair Manual edition that had straight-up left a step out of the confirmation pattern. Found the missing step in the updated online version—well, really, Elektroingenieur found it for me—and good to go.)

    And, second, for times when you don't want to check for later corrections online, but you see something in the Repair Manual that looks like it might be a goof, it's ok to think it might be a goof. You don't have to limit yourself only to possible explanations that preserve the inerrancy of the Repair Manual. It's allowed to ask questions like "if this was a goof, what did they probably mean?".
     
    #161 ChapmanF, Apr 22, 2026
    Last edited: Apr 22, 2026
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  2. Brian1954

    Brian1954 Senior Member

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    I never had a problem with the hybrid battery in my 2011 Prius, so there was never a need to clear a permanent P0A80 code.

    One thing you seem to be missing in your written description of the Universal Trip Driving Pattern. It needs to be 10 minutes or more in total time, not just the 5 minutes or more driving above 25 MPH.

    I trust the Autell AP200 to read all the trouble codes on a Gen 2 or 3 Prius, so if you do a complete scan and find no codes, then it is ready to get the smog inspection done. I do not care if any of the other scanners that you own show a permanent code.
     
    #162 Brian1954, Apr 22, 2026
    Last edited: Apr 22, 2026
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  3. PriuSocal

    PriuSocal Member

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    Actually, since you mention it off topic, I do fit the bill as one of those who believe the Bible is completely inerrant in every word. And its definetly not based on “denomination” its based on whether you are a true believer or not and have reviewed the facts. The questioning lies on “interpretation” and not “denomination” IMO ;)

    On the actual question, I rest my case as Im sure of there was someone who would have had success, it would have came up on all the posts regarding P0A80 in this forum.
     
    #163 PriuSocal, Apr 22, 2026
    Last edited: Apr 22, 2026
  4. PriuSocal

    PriuSocal Member

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    Oh, it wasn't missed just not questioned in the procedure. But yeah that part was done each of the 2 times I tried the procedure.

    As for the trusting the AP200, I had that question somewhere in the last 8 pages where I inform that the permanent code doesnt show on the Autel based scanners and only on my BlueDriver scanner. The AP200 even shows IM readiness at a ready for smog phase. Further online research showed that “certain” scanners may not show “certain” permanent codes and only current or pending and one of those scanners on the list was the Autel based scanners and word of caution was to go by the one that actually showed it because it wouldnt continue to show if it wasn't there.

    I also mentioned how the smog guy here in CA concurred with some scanners not showing permanent codes and then them showing up on their computer which is linked to the state and if it does show on their end, it will automatically fail with no pre test available for this type of code since they use a scanner of their own to pretest if the car has any current issues and if none show on their scanner (dont know what type of scanner they use) they run it but have had moments where their scanner shows clear and the when they hook it up to the states system, the permanent comes up and fails.

    That was my dilemma since I do need to smog it here in CA to get it registered and thats the only thing pending to get my tags from and finalize the title transfer. They are willing to try it but theres that asteRISK that exists and I have to be willing to take it if I want to “find out” if indeed the code is not really there like the AP200 and my Icon T10 suggests.
     
    #164 PriuSocal, Apr 22, 2026
    Last edited: Apr 22, 2026
  5. Brian1954

    Brian1954 Senior Member

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    From website, (US Ship)Autel MaxiAP AP200 Bluetooth OBD2 Scanner Auto Car Check Engine Light Code Reader for Family DIYers – AutelShop.us

    Functions:
    1. ....
    2. ....
    3. COMPLETE OBD2 FUNCTIONS:

    1. Read extensive current, pending and permanent codes in OBD system quickly
    .....

    You wrote in post #68:
     
    #165 Brian1954, Apr 22, 2026
    Last edited: Apr 22, 2026
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  6. PriuSocal

    PriuSocal Member

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    Correct.
     
    #166 PriuSocal, Apr 22, 2026
  7. ChapmanF

    ChapmanF Senior Member

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    I know there are denominations confessions groups of Christian-identifying people who hold the position you hold there, and other groups of Christian-identifying people who do not, and saying which ones are right is above my pay grade. For the purpose of this thread it doesn't matter, because the key on-topic point of my post is that no such treatment is merited by the Toyota Repair Manual. That's a book we know can have mistakes. :)

    So if you come at Repair Manual interpretation using the same approach you have to use when treating a different book as inerrant, you can miss possible simpler answers to puzzling bits.
     
    #167 ChapmanF, Apr 22, 2026
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  8. ASRDogman

    ASRDogman Senior Member

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    Just drive it. However you normally drive. Eventually it will go away.
    If the issue that threw the code is repaired, according to Toyota.

    It will take a few cycles for the mileage to equal out.
    Just use the same station, and the same pump each time. Fill up the same way each time.
    That way you can get the most accurate readings.

    I believe you said you disconnected the 12v battery, so it resets everything.
    The computers learn how you drive, and the accuracy of the guestamite will get closer
    to the real thing. The best way is to reset one of the trip meters when you fill the tank.
    drive to about half a tank, fill up and write down the mileage. Then divide the mileage by
    the number of gallons.

    Enjoy the car!



     
    #168 ASRDogman, Apr 22, 2026
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  9. PriuSocal

    PriuSocal Member

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    Something funny happened yesterday.

    A friend who has a 2012 called me saying they had the RTOD come up on theirs and wanted me to check it out for him. He brought it over and immediately I noticed the car would not shut off even when parked. I ran a scan and what do you know, P0A80 as current, pending and history/permanent. He stated he had been driving the car like this for about 2 weeks. Like Avril Lavigne said…. “And isn’t it Ironic…Don’t you think? It’s like Crayyyyzayyyy” LOL.

    However, not entirely a bad thing. Why you ask? Well, it allowed me to see another side of this P0A80 code and compare symptoms from his car to mine and they are similar in the fact that both cars are running well and he even says his MPG is in the mid 40’s still, but night and day in others. His car has 206k and he has only done basic maintenance on it since he bought it 2 yrs ago (oil, brakes, tires etc). I checked the HV blocks while car was on and most blocks were hovering in the low 16v’s and 5 and 6 were on the mid to high 15v’s, at times reading 0.4v-0.5v under. I shut the car off and deleted the codes, then when I turned it back on, the car would now stay on for 5-10 secs and then shut off like they normally do and battery was holding steady charge at minus 2 bars from full. Something the car was not doing before since it would stay on constantly and most likely PCM recognizing weak cells/blocks and constantly sending a charge which would not hold on its own.

    Here are the key differences noticed from his car to mine with a permanent P0A80. With car A being his and B being Mine
    A.
    1. Showing permanent P0A80 on the AP200/T10 scanners
    2. Multiple blocks at -0.4v-0.5v
    3. P0A80 came back on after 2 hours
    4. Has slight death rattle at startup

    B.
    1. Not showing the permanent code on AP200/T10 (only showing on BlueDriver)
    2. All blocks show consistent similar readings
    3. No CEL or current codes present so far after 1k+ miles
    4. No death rattle

    i know the last difference could be unrelated and more a possibility in relation to EGR side of things (if that), but we will be going into the battery and checking the condition of the busbars/nuts as well and testing each modules voltage at static and under load to get a clearer picture.

    I am beginning to feel more aligned with @ASRDogman that my car may just need to be driven and perhaps this code will resolve on its own after some drive cycles. Also, with the OP who mentioned taking it to the smog place and taking a chance at smogging it and it not appearing on their side either has become a plausible idea.
     
    #169 PriuSocal, Apr 23, 2026
    Last edited: Apr 23, 2026
  10. PTS

    PTS Member

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    His battery is toast and it is very possible he has a head gasket leak.

    When I had a permanent P0A80 the only thing that cleared it was a replacement. Prior to that, the Toyota documented or the internet modified Confirmation Driving Pattern failed.

    After replacement it cleared by itself in a day.
     
    #170 PTS, Apr 23, 2026
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  11. PriuSocal

    PriuSocal Member

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    You referring to a “replacement” of what the battery fixed your issue? I feel that way as well in his case. Good thing is he is prepared to get a replacement HV battery if it indeed is the issue. As for the death rattle, HG issues usually have underlying and visual symptoms like coolant loss as well as washed out cylinders etc. He is not experiencing coolant loss at least. It could be the beginning of such issue though and at this time, you start by the EGR, TB and Intake Mani cleaning and sometimes that does the trick for that, also dirty or failing injectors can cause that as well.
     
    #171 PriuSocal, Apr 23, 2026
    Last edited: Apr 23, 2026
  12. PriuSocal

    PriuSocal Member

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    I recently got a chance to use techstream from a buddys computer. My first impression is none lol, the interface is that of a 90’s software and very slow BUT it is indeed very powerful tool for any Toyota owner. Well, I had read that it contains repair procedures and this is where the drive cycle instructions to clear certain codes comes from, just like the one we have been talking about here that everyone copy/pastes for the P0A80 code. Where do I find that in the techstream software? I was told this laptop is only used offline so not sure if you need internet to see that info. Does anyone know which tab to look in?

    Thanks
     
    #172 PriuSocal, May 29, 2026 at 2:52 PM
    Last edited: May 29, 2026 at 2:59 PM
  13. ChapmanF

    ChapmanF Senior Member

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    Exactly—a confirmation driving pattern should only be expected to make a permanent code go away when it is able to confirm (!) that you have fixed the original problem. Nobody should ever expect a confirmation driving pattern to confirm that you fixed a problem when you didn't.

    After a successful repair, permanent codes sometimes go away more quickly than other times. The confirmation driving patterns are provided for those other times, if you have a need to hurry the process along.
     
    #173 ChapmanF, May 29, 2026 at 3:07 PM
  14. rjparker

    rjparker Tu Humilde Sirviente

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    You have to have an online subscription to TIS. There are no Toyota compiled manuals like in the old days. The pdfs are located online and have hotlinks that only work online. However you can pay for a two day access ($30) and download hundreds of pdfs one at a time.

    There are non-indexed patched together versions of many pdfs floating around. No functional links as well and the most common version is for a 2010.

    TIS

    The hacked Techstream only works offline even if you pay for access. The instructions from the seller say turn off your virus checker or it may not work. If you do go online Toyota can detect it and disable it.

    Toyota has a new version you can download and use for 2 days ($80).
     
    #174 rjparker, May 29, 2026 at 3:08 PM
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  15. PriuSocal

    PriuSocal Member

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    Ah ok, i figured you needed to be online. Thanks for the feedback and confirmation on that. To subscribe do I have to download techstream on my laptop first or will it be access to just the website? That may be worth to go on there and download binge.
     
    #175 PriuSocal, May 29, 2026 at 3:19 PM
  16. ChapmanF

    ChapmanF Senior Member

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    When somebody says Techstream "contains" repair procedures, generally that just means that Techstream (when you're online, and using a non-hacked copy) has a lot of places where it will link you into the relevant place in the online repair manual, which is where those procedures come from, including the ones that get pasted and talked about here.

    Toyota Service Information and Where To Find It | PriusChat

    There are some rare exceptions, like the brake bleeding sequence, where it really is Techstream that prompts you through the right order of doing things, and the repair manual just says to start the bleed procedure in Techstream and follow the steps as it prompts you. (Which is frustrating if you're trying to study ahead in the manual and prepare for what you'll be told to do.)

    But anyway, for the most part, the repair manual is where you find procedures and explanations, and you just use Techstream (or some other comparable scan tool) as your tool to carry out what's in the manual.
     
    #176 ChapmanF, May 29, 2026 at 3:35 PM
  17. PriuSocal

    PriuSocal Member

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    On another note, as you can see how this thread had lots of questions about the exact meaning steps to take and some were able to agree with me that there were discrepancies in the drive cycle about steps to take within the universal trip of wether or not the car had to be/stay/driven in inspection mode and about the car needing to be ON READY or OFF since the latter is required to go into maintenance mode. I was able to get a clearer understanding on the discrepancy of the information provided by Toyota for the confirmation cycle / Universal trip. After hours of searching and putting info I found into order using various search prompts and lots of back and forth that I hope this helps clarify areas where I was confused for a long time hence no confident answers provided. Many already know but to have it all on one place let’s establish what each mean first:
    • Confirmation drive cycle = the full dealer/service procedure to verify a repair or reproduce/confirm a specific DTC (it includes multiple setup and test steps, and may vary by DTC).
    • Universal trip = a standardized short drive segment used inside some confirmation drive cycles (the universal trip’s idle/drive/wait steps are performed as part of the larger confirmation drive).

    So lets look at the CONFIRMATION DRIVE CYCLE steps as described by Toyota 1st:

    1. Connect vehicle to Techstream
    2. Turn the Power switch ON (IG) and turn the Techstream on
    3. Clear the DTC’s (even if NO DTC’s are stored, perform the DTC clear procedure)
    4. Turn the power switch ON (Ready) and turn Techstream ON
    5. Perform a UNIVERSAL TRIP

    This is where the discrepancy happens, between step 4 and 5 there is a contradiction (at least with no clarification from Toyota included) BUT lets wait a min and skip promptly to the UNIVERSAL TRIP and you’ll understand...
    • Universal trip (inspection-mode universal trip) steps:
      1. Put the vehicle into Inspection (Maintenance) Mode. (BUT VEHICLE NEEDS TO BE OFF TO PUT IT INTO MAINTENANCE MODE!)
      2. Idle the engine for 30 seconds or more.
      3. Drive the vehicle at 25 mph (≈40 km/h) or more for a total of 5 minutes or more.
      4. Allow at least 10 minutes to elapse from the time the engine was started before turning the power off.
    6. With the select lever in N (neutral), leave the vehicle until the SOC drops to 30%
    7. Enter the following menus: Powertrain/Hybrid System/Trouble Codes
    8 Check that the Permanent DTC’s are cleared.

    These steps are quoted verbatim in Toyota repair procedure entries for confirmation-driving patterns (for example, the P0A80 confirmation drive in Toyota TIS).

    For which I replied the following :
    “OK, but step 5 of the confirmation drive says turn the power switch to READY (ON) and turn Techstream ON BUT, to put the vehicle into inspection mode you have to have the car off. SO its contradicting so I need clarification on that as its not clear"

    Response:

    You're right — that wording is confusing. Here's the clarification used in Toyota TIS repair steps:
    • (Maintenance) Mode" is entered with the hybrid system OFF (power switch OFF) to allow certain checks and to enable the universal trip sequence setup.
    • The universal trip itself begins after those initial setup steps. For confirmation-drive procedures that say "turn the power switch to READY (ON) and turn Techstream ON," they mean: first complete the Inspection Mode / setup steps with the vehicle OFF as required, then EXIT inspection Mode and restart/turn the power switch to READY to perform the Universal Trip driving portion while Techstream is connected and running.
    So that indicates that steps 4 & 5 are flipped around and one prompt missing, according to the info above, so based on the provided info I believe the clarified version of the Confirmation Drive + Universal Trip could possibly be this instead:

    1. Connect vehicle to Techstream
    2. Turn the Power switch ON (IG) and turn the Techstream on
    3. Clear the DTC’s (even if NO DTC’s are stored, perform the DTC clear procedure)
    4. Turn vehicle OFF
    5. Enter Maintenance Mode
    6. Exit Maintenance Mode by turning vehicle OFF
    7. Turn the power switch ON (Ready) and turn Techstream ON
    8. Perform a UNIVERSAL TRIP (the remaining portion) :
    -     Idle Engine for 30 seconds or mode
    - Drive the vehicle at 25 mph (≈40 km/h) or more for a total of 5 minutes or more.
    - Allow at least 10 minutes to elapse from the time the engine was started before turning the power off.
    9. With the select lever in N (neutral), leave the vehicle until the SOC drops to 30%
    10. Enter the following menus: Powertrain/Hybrid System/Trouble Codes
    11. Check that the permanent DTC’s are cleared

    I will be trying this as soon as I have a day off BUT if anyone decides to try it, let me know if it works or not.
     
    #177 PriuSocal, May 29, 2026 at 6:18 PM
  18. ASRDogman

    ASRDogman Senior Member

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    Is that an authorized version or pirated version?
    If it's pirated, do NOT connect to the internet! Turn off wi-fi so it doesn't.
    Since you said it's slow, it could be the cable used, or speed of laptop, or because it's a
    pirated version, or combination.

    I hope it works for you and clears the code!

     
    #178 ASRDogman, May 29, 2026 at 6:36 PM
  19. ChapmanF

    ChapmanF Senior Member

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    I agree with the chatbot that the best way to get past the contradiction in details is to drop any assumption that the repair manual is word-for-word inerrant, so then our mission (should we choose to accept it) is to try to reason out what the authors most likely intended.

    If that's the mission we've accepted, there's still room for different guesses. The chatbot's guess that the authors would have intended to enter and then just immediately exit maintenance mode would not be my own first guess. (My own first guess was upthread in #109.)

    But the chatbot did say «Here's the clarification used in Toyota TIS repair steps», and further «For confirmation-drive procedures that say "turn the power switch to READY (ON) and turn Techstream ON," they mean: first complete the Inspection Mode / setup steps with the vehicle OFF as required, then EXIT inspection Mode ....».

    If you didn't ask the chatbot to supply its exact source for saying that, resuming the chat to pose that question might be worthwhile. Maybe the bot actually has found some 'clarification' in TIS that says that, which would be good for us to know. Alternatively, I've also seen such chatbots just make stuff up, which would also be good to know.
     
    #179 ChapmanF, May 29, 2026 at 6:48 PM
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