2005 Prius, Gen 2, code P0A09, Hazard and car symbol with exclamation point

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by MaryCarol, Jan 23, 2025 at 1:59 AM.

  1. MaryCarol

    MaryCarol Junior Member

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    Location:
    Palo Alto, CA
    Vehicle:
    2005 Prius
    Model:
    N/A
    Hi there,
    Y’all have been so helpful in the past- and online searching hasn’t helped this time- so wondering if anyone has advice here…

    My car sat for 3 months while I was away and the 12 volt appeared to have died and was not charging well (bad battery according to neighbors trickle charger) so I got a new 12 volt today - the previous was under warranty and only a year old.

    After the installation, I saw the Hazard with exclamation point on the dash and then the car symbol with exclamation point on the screen. Which indicates a big problem.
    The man at autozone said the code was
    P0A09 and he suggested I drive the 2 miles home and then try to drive 50 miles in the next few days and see if that clears things out. However if something is seriously wrong, I don’t want to drive it or hurt it. And when I searched the code online, I found something about a hybrid DC converter failure. I’m hoping the hybrid battery (expensive) isn’t the problem bc the car itself is only worth about $4K at this point.

    The car is 20 years old, I am second owner and have had it 10 years exactly and it has just under 110K miles. Which I know is shockingly low. It will be due for an oil change and check up in about 300 miles, but since it was sitting for a few months, my next move may be to take it for an oil change and check up at a local place 2 miles away. (I did pump up the tires already, just to state the obvious).

    The big question- is this the hybrid battery and a super expensive repair I’m looking at?
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Vehicle:
    2009 Prius
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    Base
    The car's not even broken in good yet but it's at the point year-wise like 20 years old almost where the brake actuator and things are going to start to fail but if you think those things are going to equal a new car better think again in this market even buying a new or refurbed hybrid battery handling the break actuator when it happens and the myriad of other little things that can go wrong you are still way ahead of a I don't even know what $15,000 something another and a payment easily especially if you can do anything yourself this is a pretty easy car to work on as far as taking things off and putting them back on with some basic hand tool seriously You don't need anything special for the most part to work on this car except for a reasonable scan tool if you're going to tackle the brake work and now you can do something with that for like $70 If you think this is costly well you haven't worked on much stuff or anything like that I guess doesn't get much cheaper.
     
  3. Tombukt2

    Tombukt2 Senior Member

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    Vehicle:
    2009 Prius
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    Base
    The code you have right now is about the circuit that charges your 12 volt battery which runs all of your car except for the electric motors in the transmission and your air conditioning that's high voltage. So your car's inverter apparently isn't charging the 12 volt so now you're running the brand new 12 volt into the ground what you going to want to do here generally is just replace your inverter what's broken is on the bottom of your existing inverter which apparently is working fine The DC to DC converter that charges the 12 volt that circuit has gone bad. Generally it's a pain in the rear end change it it's easier to change the inverter complete they're plentiful they're everywhere junk yards are throwing them away so just grab an inverter from a tow lot LKQ a junkyard anywhere you can get one relatively cheap say let's say $100 or less something like that like I say they can't get rid of these things so happy to take a hundred bucks. Plug that up screw it down and start the car up and check the 12 volt with the car in the ready mode it should show about 13.4 to 14.5 volts with the ready light on and you should be good to go also make sure all of your fuses are good there are some fuses I think that have something to do with charging and all that You want to make sure you don't have any blown fuses they make little doodads to test your fuses right on the car they light up they come in a yellow container made by a company called b u s s and good luck.