Shift system malfunction

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by ButterflyPrius, Apr 25, 2025 at 3:47 PM.

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  1. ButterflyPrius

    ButterflyPrius New Member

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    Hello, and thanks in advance for your help. The heat wasn’t working in my 2016 Prius with 156k, and the mechanic said it was the water pump. After replacing the water pump, they said it was a problem with the engine because it wasn’t drawing the coolant into the engine. So after replacing the engine with a used one with 43k, the heat still wasn’t working and the problem is allegedly the heater exchanger and catalytic converter, which are on backorder. So the heat won’t work until those parts are in but the car is allegedly safe to drive. But wait, there’s more: the temperature light started blinking, so I took it back and one of the “new” engine’s gaskets needed replacing. Done, and the same day, I tried to put the car in Park and got the message “Shift system malfunction, apply parking brake securely when parking, see owner’s manual,” and nothing would happen when I pressed Park. Straight back to the mechanic, who says that is probably an issue with the auxiliary battery, to which I call BS because that battery was replaced less than a year ago.

    So, wondering if anyone has had the Shift System Malfunction warning, and if it’s truly just a battery issue or something to do with the engine and/or incompetence. Thanks for your help.
     
    #1 ButterflyPrius, Apr 25, 2025 at 3:47 PM
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  2. Mendel Leisk

    Mendel Leisk Senior Member

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    How long have you had it?
    The exhaust heat recovery system, which is integrated with the catalytic converter, a single unit at the head of the exhaust system, has proven prone to coolant leaks in early fourth gen years.

    Still, it’s readily apparent this guy’s just throwing parts at it, significant parts. I’d walk away from this mechanic, get a fresh set of eyes on it. How much has all this cost?
     
    #2 Mendel Leisk, Apr 26, 2025 at 6:45 AM
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  3. bisco

    bisco cookie crumbler

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    i would recommend a prius aware code reader. i'm very sorry that you have been taken advantage of by an unscrupulous 'mechanic', and i hesitate to call him that
     
    #3 bisco, Apr 26, 2025 at 1:53 PM
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah an engine is one heck of a "part".
     
    #4 Mendel Leisk, Apr 26, 2025 at 1:59 PM
  5. bisco

    bisco cookie crumbler

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    correct me if i'm wrong, but the exhaust heat exchanger wouln't contribute to the heat not working at all, unless all the coolant drained out, in which case the coolant reservoir would be the obvious first clue
     
    #5 bisco, Apr 26, 2025 at 2:06 PM
  6. ButterflyPrius

    ButterflyPrius New Member

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    I'm in for 6 grand at this point. Would never have put that much into such an old car, much as I love her. Thanks for your advice.
     
    #6 ButterflyPrius, Apr 28, 2025 at 6:04 AM
  7. ButterflyPrius

    ButterflyPrius New Member

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    I've had it since 2018/34k miles. I'm hoping this is a 250k mile car, at least!
     
    #7 ButterflyPrius, Apr 28, 2025 at 6:05 AM
  8. ButterflyPrius

    ButterflyPrius New Member

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    Thank you!
     
    #8 ButterflyPrius, Apr 28, 2025 at 6:06 AM
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