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Engine Keeps Turning On In EV Mode

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by Mokey, Feb 7, 2023.

  1. Mokey

    Mokey Junior Member

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    Vehicle:
    2014 Prius Plug-in
    Model:
    Plug-in Base


    I have a 2014 PIP with about 83,000 miles total, about half of which are EV miles based on best estimate.

    The engine keeps turning on after 30-60 seconds while I'm in EV mode when I first start driving. No AC or heat or any other accessories turned on.

    This used to happen every so often if I hadn't used the engine for a week in the summer or if it was cold (< 20 F) in the winter, but now it's happening every time I drive (it is still winter here so haven't tested above 40 F).

    After the engine warms up, it will switch back to EV mode. If I turn it off and drive again 10 minutes later, it does the same thing.

    The 12-volt starter battery had 83% health when I had it checked a month ago (after leaving an interior light on and it wouldn't start at all), but I keep wondering if the engine is turning on to charge the 12-volt because it's deficient? Or something else?
     
    #1 Mokey, Feb 7, 2023
  2. sam spade 2

    sam spade 2 Senior Member

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    Something else.

    The engine does NOT directly charge the 12 V battery.
    That is done with an "inverter" from the HV battery.

    A lot of things can change slightly over 9 years and 83K miles.
    I suspect it's just old age.......kind of like my arthritis.

    It is still possible that a weak 12 V battery is contributing to that behavior......but I think it's a real long shot.
    Might want to have it tested again.

    With non-pip models, that can be an early warning sign of the HV battery getting weak.
     
    #2 sam spade 2, Feb 7, 2023
    Mokey likes this.
  3. bisco

    bisco cookie crumbler

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    how many miles of range is it estimating when you turn it on?

    are you sure the front defrost isn't on?

    have you tried a flat route under 30mph?

    definitely get the 12v load tested
     
    #3 bisco, Feb 7, 2023
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  4. Mokey

    Mokey Junior Member

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    2014 Prius Plug-in
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    Plug-in Base
    thanks for the suggestion
     
    #4 Mokey, Feb 7, 2023
  5. nicoj36

    nicoj36 Active Member

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    This is only in the winter when temperature is low and its necessary to warm-up the engine just in case gas is needed. Mine is the same thing. Summer and spring it doesn't kick in.
     
    #5 nicoj36, Feb 7, 2023
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