P0A94 and P0A7A

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Islanderfan17, May 27, 2025 at 10:51 AM.

  1. Islanderfan17

    Islanderfan17 New Member

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    Hey all,

    I have an 08 Prius that originally I started working on due to heating issues paired with a red triangle event one day that had my car shut itself down on the side of the highway. Having had a similar overheating issue with this car in the past, the first time it was fixed by replacing the three way coolant control valve, which I did this time as well along with replacing the thermostat and inverter pump. I also changed out the coolant in both systems using the airlift suction system.

    At one point I had tried getting to the auxiliary water pump and also removed the inverter cover and disconnected the three orange plugs in the back to gain access to that area, but I reversed course on that because it was too difficult to get everything apart back there. I put it all back together. I also had to replace the 12v battery in the vehicle because it died while sitting for awhile (life has been busy, I couldn't work on the car for a bit). Early on with all of this, I also swapped out the hybrid battery with the one from my wifes 04 Prius that I am currently using because my 08 had the better and newer battery (it was a replacement OEM new battery from probably 5ish years ago, still in great condition).

    So needless to say A LOT of little things have been done with the car since this all started. I went to drive it after having everything back together recently and instantly the car shuddered and a red triangle came up along with I believe the ABS light and another one I don't remember right now (VSC?)

    The codes are a P0A94 and P0A7A. I do not have tech stream so no further details beyond that. The heating in the car also STILL doesn't work.

    Could this be that the inverter has gone bad and needs replacing?
     
    #1 Islanderfan17, May 27, 2025 at 10:51 AM
  2. dolj

    dolj Senior Member

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    Both of those codes have several sub-codes, and it would be useful to know which ones you have. It will simplify the diagnosis steps.

    In any case, for all sub-codes of the P0A7A, which relates to the inverter/converter, the first trouble area to look at is the wire harness or connector. As you've had one of the harnesses off the inverter, you should look there and double-check your work.
     
    #2 dolj, May 27, 2025 at 12:00 PM
    Brian1954 likes this.
  3. Tombukt2

    Tombukt2 Senior Member

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    You got some serious connection issues my friend I do believe unfortunately you're going to have to open everything back up and have a look again Google the codes it'll tell you what they're about monogenerator one performance and the DC to AC and reverse converter it doesn't seem like all that would be bad at one time it seems like something's connected wrong not connected not tight I'm not sure or this car had all this problems to begin with and well there you go usually not though. So I would go back over all my connections and everything you took the top of the inverter off and got to look in there and thought it was too complicated oh boy so all the plugs are plugged back up and all the silver screws or in all of the orange wires through their connectors plug through the body of the inverter assembly all the plugs on the back of the inverter are plugged in and so on because this is pretty serious stuff if everything looks good and everything is connected the drive motor a performance thing is a serious problem that's all in the transmission you don't want any part of that most people never see it very few do looks like you may be one of them.
     
    #3 Tombukt2, May 27, 2025 at 12:01 PM
  4. Islanderfan17

    Islanderfan17 New Member

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    Thank you for the reply! I believe I plugged back in the inverter properly considering it's fairly simple putting it all back in connector wise, it's really just the orange plugs which are very straight forward. I was missing some of the screws holding the inverter cover down but had most of them, maybe missing a few. I can't imagine screws holding down the case would cause issues?

    But I will go back and do it again regardless.
     
    #4 Islanderfan17, May 27, 2025 at 1:11 PM
  5. dolj

    dolj Senior Member

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    Believing and checking are two different things.

    The missing screws might be a thing if they cause the safety interlock on the inverter to not close properly.
     
    #5 dolj, May 27, 2025 at 11:56 PM
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