P0A72 and P0A7A codes

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by logbiter, Sep 28, 2025 at 1:03 PM.

  1. logbiter

    logbiter Junior Member

    Joined:
    Mar 17, 2018
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    Location:
    Lafayette, LA
    Vehicle:
    2005 Prius
    Model:
    II
    This morning, when I turned on the car (2005 178k miles), all the “bad” lights on the dash lit up. The DrPrius app showed two battery error codes: P0A72 and P0A7A. I cleared the codes, but they come back.

    -The inverter cooling pump is staying on w/ rippling in reservoir. I replaced it (Aisin) a few months ago.
    - motor doesn’t appear to be charging hybrid battery.
    - 12v battery tests OK. 12.4V w/ decent SOC. It is 5 yrs old.
    - this is the first morning with the temperature dropping to 65 degrees Fahrenheit. It’s freezing, I know! I’m in Cajun country.
    - recent DrPrius battery tests were above 60% life expectancy on original battery.

    So, anything else I can check with my middling DIY skills?? I'm a bit leary of checking high voltage stuff, but do have a multimeter & and am familiar with basic electrical stuff.
    OR time to take it to a shop? If so, tow or would it be OK to drive up to 20 miles to the shop? The dealer I trust is 20 miles, but there's a shop that a bunch of Toyota Techs opened up ~10miles away. I'm not sure about their hybrid experience though... the guy working the counter when I took it there for some AC work recently told me hybrid batteries for my Prius aren't available anymore. Which seems sus.

    Also- recommended iOS apps for my bluetooth OBD2 reader (nexas)that will give me a better drill down on the codes?

    -I can get use of a computer with old version of techstream on it, might take a day or so.

    Thanks for any advice!
     
    #1 logbiter, Sep 28, 2025 at 1:03 PM
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  2. bisco

    bisco cookie crumbler

    Joined:
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    Vehicle:
    2012 Prius Plug-in
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    Plug-in Base
    autel maxi 200 seems to be the scanner of choice, after tech stream. get a free load test on the 12v at most auto parts stores to be sure it is good before scanning.
     
    #2 bisco, Sep 28, 2025 at 3:30 PM
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  3. ChapmanF

    ChapmanF Senior Member

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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    DrPrius is mislabeling those as 'battery' codes. They are about the hybrid system, but not about the battery. They are also not about the cooling pump. P0A7A "generator inverter performance" is about the inverter circuit that's responsible for MG1, and P0A72 "generator phase V current" is about an abnormal reading of current from the inverter into the V-phase winding lead of MG1.

    These are not among the common familiar issues with simple things to look at. It would be best to look up those codes in the repair manual directly, to be able to follow the (probably several pages of) troubleshooting instructions there.

    Toyota Service Information and Where To Find It | PriusChat
     
    #3 ChapmanF, Sep 28, 2025 at 3:50 PM
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