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Red triangle but good mpg

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Dahvid, Aug 30, 2024 at 3:49 PM.

  1. Dahvid

    Dahvid New Member

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    Looking at buying a prius. Owner says mobile mechanic said cell 10 was low but still in range. They just took a roadtrip and still got over 40 mpg. It also won't start until codes are cleared; has red triangle

    I guess my questions are:

    Can you still get mpg like this with a bad cell?
    Could it be the 12v starter battery that's causing this?
    I'm more concerned it could be something else. Any thoughts?

    I hope that's enough information.
    Thanks for any and all input.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    More than likely you have the hybrid isolation fault this requires you to clear the code to generally drive the car starts and drives normally charges relatively normally gets pretty normal gas mileage and so on
     
  3. Dahvid

    Dahvid New Member

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    So a hybrid battery replacement is likely the cause? I just want to make sure it's nothing like an inverter or other problem. Sounds like a battery replacement is pretty straight forward
     
  4. Brian1954

    Brian1954 Active Member

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    What are the trouble codes that are being cleared? List them, and you will get some answers about what the problem is with the car.

    PS, do not buy an old Prius unless you have experience fixing cars. Old hybrid cars can be very expensive to fix if you can not do the work yourself.
     
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    The P0AA6 code is the ONLY (hybrid system RTOD) code that will allow you to continue driving normally until you shut the car off. At that point, it locks you out of going READY, so the next time you need to use the car, you need to reset the codes by disconnecting the 12v battery for a minute. If the P0AA6 is being caused by the HV battery, this can be caused by HV battery modules that are still in excellent condition (capacity wise) but have developed a voltage leak to the steel battery case. Sometimes this is caused by electrolyte leakage. Sometimes it is caused by microcracks on the bottom of the module where the small machine screw fastens the module to the case. The screw threads into a metal insert that is pressed into the plastic body. Sometimes it will develop a crack allowing electrolyte inside to make contact with the insert. Sometimes this can be solved just by putting a piece of electrical tape under that module and leaving that screw out.

    If it's a P0AA6, 90% or more of the time it's a battery issue. Can also be AC compressor motor, inverter, cables, transaxle, etc.
     
  6. mr_guy_mann

    mr_guy_mann Senior Member

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    Could be, battery faults are a common cause for isolation codes, but I would want to check all systems for codes with a capable scantool.

    Here's a thread that reviews several apps and devices for a smartphone. You would want one that can retrieve INF sub codes to get more details about the fault.

    INF codes are located in freezeframe data. For P0AA6, you want to try and power up the car twice - it won't go ready the second time. The first time sets a 526 "general" isolation fault INF. The second time will set another INF that narrows down the fault area.

    https://priuschat.com/index.php?posts/3290690

    Posted via the PriusChat mobile app.
     
  7. Dahvid

    Dahvid New Member

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    Thank you for the replies everyone
    I just confirmation that p0aa6 is showing with 5 other codes

    I can maybe swing $2k for it and with a little elbow grease in figuring out these codes and those issues I'll have a decent daily driver
     
  8. Dahvid

    Dahvid New Member

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    If it were the batteries leaking, would it be incredibly dangerous to drive it?

    Just want to see how much time I would have in getting around to fixing it.

    I'd be ok with diving in and solving/ fixing this myself I would be so proud of myself

    If it's just a couple of cells leaking I could swap those out I imagine? I know it's probably easier said than done. Would I have to buy one of those tenergy chargers and balance the pack again? I figure that may be cheaper/ more reliable than switching out the entire pack?

    I figure I swap out bad cells or just swap the entire pack.

    I'm not necessarily looking at the easiest route but the most reliable then I suppose the most cost effective. I realize everything is a compromise
     
  9. Dahvid

    Dahvid New Member

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  10. Dahvid

    Dahvid New Member

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    Sorry I may have posted this in a weird way
     
  11. ChapmanF

    ChapmanF Senior Member

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    A P0AA6 code can often turn out to be something fixable without spending nearly that much. It is not the kind of code that has to mean the battery modules are badly worn out in capacity or anything. Even if the isolation fault is within the battery (INF code 612), it might be something than a module leaking electrolyte, and even if it is a module leaking electrolyte because of a small crack, say, there could be a good argument for just replacing that one. (This can be in contrast to, say, P0A80, which usually appears when all the modules are pretty bad capacitywise, and efforts to replace just one or two worst ones often turn into whac-a-mole.)

    A lot comes down to what you find when diagnosing the P0AA6.

    You haven't said what the five other codes are.