2007 Transmission Temp Sensor - P0A2B, P0A2C, P3102

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by rhysmmd, Aug 10, 2023.

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  1. rhysmmd

    rhysmmd New Member

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    Aug 10, 2023
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    Location:
    Oakland CA
    Vehicle:
    2007 Prius
    Model:
    N/A
    My 2007 Prius (~193k miles) recently threw the red triangle signal after driving for ~50 minutes on the highway, and there was a louder whine than normal along with some jolting back and forth when accelerating. I pulled over and had it towed into a shop (who work on Prius's regularly, although aren't specifically hybrid specialists) that retrieved the following codes: POA2B, POA2C, P3102, indicating transmission temperature circuit issue. They checked the wiring, inverter cooling system, coolant level, and inverter pump and found no issues. They suggested that it was possibly a faulty sensor or connection; not clear what it was caused by but the whining noise may indicate the motor being loose and causing the faulty connection (just one theory they tossed out).

    Because the temperature sensor is serviced in the motor assembly, I would have to replace the whole hybrid motor and tear down the transaxle system in the process (per the shop, who weren't willing to do this and I'm hoping to avoid it, because I'm not convinced it would definitely solve the issue and would be costly). Alternatively, they suggested I could try driving it around after the codes were cleared, so I did and it was fine for about 10 minutes of city driving and but then immediately after getting on the highway, it threw the triangle again and I took it back to the shop.

    I'm not necessarily looking to sink a bunch of time and/or money into the car at this point (has been pretty reliable since we got it in 2008, but I'm not in situation where I can do much DIY work on it) - has anyone experienced something similar, and would anyone recommend taking it to a hybrid specialist or transmission shop? Otherwise, I may just try and unload it.

    -Rhys
     
    #1 rhysmmd, Aug 10, 2023
  2. PriusCamper

    PriusCamper Senior Member

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    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Sure would be nice if there was a way to get a temp reading in a different way to verify it's not an issue? Alternatively or additionally, having a Blackstone analysis done on the transmission fluid would tell you specifics about any metal inside the transmission wearing away, which would likely be the reason a normally functioning temp sensor would warn you.

    And in general, the Gen2 transmisison rarely if ever has an issue... There was some fried stator problems with Gen1 Prius but they resolved that in Gen2 and haven't seen anything on here about them in the past decade.
     
    #2 PriusCamper, Aug 10, 2023
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  3. Tombukt2

    Tombukt2 Senior Member

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    Nov 29, 2020
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    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    I just disassembled an engine and transmission assembly from a generation 2 or did most of it anyway and I saw a bunch of these sensor wirings that go through the transmission case go to another plug then it runs way into the transmission where you can't see there's like three or four of them they all have gray plugs they're all about level with the front side of the engine like when you're looking at the cylinders standing in their correct positions and then look over it the transmission you'll see these gray plugs You can even undo the metal plates where the gray plugs are situated right next to when you do that you'll see these real thin wires and these other plugs that go deeper into the transmission to the actual sensor It may be possible that one of these plugs that's behind the metal plates has become compromised some kind of way and then from there and even from the gray plug you should be able to measure the value of the sensor if they're just regular temp sensors they should be pretty common in the test values should be available in the manual from somebody here that does a lot of electrical work etc.
     
    #3 Tombukt2, Aug 11, 2023
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