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DTC P0A9C - How to Diagnose Issue

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriusDrift, Jan 18, 2020.

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  1. PriusDrift

    PriusDrift Junior Member

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    Hi everyone,

    I have a '06 Prius with about 150k miles that I have owned for 6 yrs. I now have the red triangle with an exclamation point showing on my combo meter, my car has trouble accelerating at times, and when the car has trouble accelerating the HV battery fan turns on full blast. I read these symptoms could indicate a dying battery, but I did just replace both batteries 3 yrs ago. I am pulling the DTC P0A9C using an obd II by BAFX. I read that this DTC indicates a damaged or obstructed hybrid battery temperature sensor, but I am not too sure and hoped you guys could provide some troubleshoot/diagnosis recommendations. My temps sensors are reading as follows: HV Battery Temp 1 - 52.16F; Temp 2 - 51.17F; Temp 3 - 51.656F. Thus, no divergent temps like some others have had.

    I am a college student new to working on my car to save money, but I did successfully change the instrument cluster a few months back so I'm hoping I can DIY fix this. Any suggestions/advice is greatly appreciated.
     
    #1 PriusDrift, Jan 18, 2020
  2. PriusCamper

    PriusCamper Senior Member

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    Welcome to our nerdiness... What app are you using to get this? Perhaps try Dr. Prius app to confirm the same code? There's potential for an inexpensive fix, but long term, pulling the pack and spending less than $100 in replacing corroded stuff, as well as reconditioning & starting spreadsheet test data for all 28 modules is the best long term solution.
     
    #2 PriusCamper, Jan 19, 2020
  3. PriusDrift

    PriusDrift Junior Member

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    Thanks for your reply and advice! I used the Torque Pro app to get this code, but I will confirm with the Dr. Prius app you recommended. For the reconditioning, I would likely need to send the battery out correct?
     
    #3 PriusDrift, Jan 19, 2020
  4. PriusDrift

    PriusDrift Junior Member

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    Update: Found my receipt and it was my local Toyota dealership that replaced it. I'm going to reach out and see if there's any warranty, especially b/c this new HV + auxiliary battery only have 20k miles on them. I tried Dr. Prius, but the app was buggy for me unfortunately. I tried a few other free apps and received the same error code back through.
     
    #4 PriusDrift, Jan 19, 2020
  5. PriusCamper

    PriusCamper Senior Member

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    Get as much for free from the Dealership as possible. You are in a very rare and ideal position to succeed with this. Also be prepared to repeatedly explain to them that you're not their to spend more money, just to get what you paid for fixed under warranty.
     
    #5 PriusCamper, Jan 20, 2020
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  6. PriusDrift

    PriusDrift Junior Member

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    Thank you, I'll let you know what happens!
     
    #6 PriusDrift, Jan 20, 2020
  7. PriusCamper

    PriusCamper Senior Member

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    Because it's a new battery, I suspect it's some part in the replacement process that wasn't replaced. Toyota stealerships often will recommend replacing the hybrid battery pack without actually diagnosing the problem because that's the fastest way to rob you of your hard earned money. I suspect whatever went wrong, could be as simple as a corroded plug, was ignored and never fixed because they were too busy raking in thousands of money that didn't need to be spent. Let us know as many additional details as possible so we can better help you?
     
    #7 PriusCamper, Jan 21, 2020
  8. PriusDrift

    PriusDrift Junior Member

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    Thank you! I agree, the dealerships are a major ripoff and the customer service doesn't seem to improve even if you are a repeat customer. At the moment, the dealership is stating I am outside of my warranty b/c apparently there is only a 1 yr warranty on a new HV replacement battery, even if installed by Toyota. This seems pretty ludicrous considering the battery only has just under 20k miles with a little over 2.5 yrs of use, and I chose new over a rebuild precisely to avoid this headache of a rebuild dying just after the warranty date. I will take my issue to corporate if I cannot resolve it with the dealership, hoping they will provide a "good will" warranty. I'll keep ya'll posted!
     
    #8 PriusDrift, Jan 21, 2020
  9. PriusCamper

    PriusCamper Senior Member

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    You might want to contact Toyota customer service and report the dealership for warranty fraud... Or at least tell the dealership that's what you're going to do if they don't check Toyota's warranty policy on replacement packs.

    You can find many examples on PriusChat where people were told the warranty is only 1 year if you install the battery pack yourself, but if an authorized Toyota dealer installs it the warranty is three years.

    Otherwise, I'll be in Sacramento area sometime in the next month visiting my elderly mom and in one hour --> $40 I can pull the pack out and find what's wrong and put it back together. Just private message me and I'll let you know soon as I get it scheduled and I'll bring all my spare temp. sensing parts. You should be ok to drive around with this problem for a little while because it's Winter and you're keeping an eye on the temp numbers. Just don't go on any road trips to the desert. :)
     
    #9 PriusCamper, Jan 21, 2020
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  10. Prodigyplace

    Prodigyplace Senior Member

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    #10 Prodigyplace, Jan 21, 2020
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  11. ericbecky

    ericbecky Hybrid Battery Hero

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    I replied over on the other thread but I'll reply here as well.

    Basically, call me and I can help you with some diagnostic stuff. 608-729-4082

    It could easily be installer error and not a part malfunction.

    Could be as simple as bumping the clip that holds the temp sensor in place.

    But as mentioned earlier in this thread, it could be a failure to check for corrosion at time of install as well.

    Not sure how handy you are or how much work you want to do yourself of it is under warranty.
     
    #11 ericbecky, Jan 21, 2020
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