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2013 prius c no codes but reduced mpg's

Discussion in 'Prius c Main Forum' started by elmo, May 26, 2024.

  1. elmo

    elmo Junior Member

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    yes. you can drive the car with the ev screen and keep the car in the green area and not the red which indicates that you are on battery only. the mpg's should rise but in my case, they actually decline. for every mile I drive I prob drop a tenth of a mile in mpg which is indicated on the screen.
    I asked the dealership about it and they said others reported similar experience but they had no clue why.
    I always was running the ac and have since I bought the car 11 yrs back. so as per rjdriver's suggestion I'm going to try running the vehicle without ac running and should c the mpgs rise if his assumption about low refrigerant is on the money. we'll c.
    can't think of anything else really that could b impactful?
     
  2. bisco

    bisco cookie crumbler

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    that sounds like a software issue. are you calculating mpg at the pump, or watching the screen?
     
  3. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    ...possibly eco mode, not ev mode?
     
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  4. bisco

    bisco cookie crumbler

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    you should be able to tell if the engine is running by sound?
     
  5. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    not everyone is sensitive to sound.

    The c does have the little "car with EV knockout" lamp on the throttle scale display in at least one of the standard dash displays. That will always be honest about whether the engine is running or not.

    I never look at that one myself, we leave our car set on the so-called "simple" display that just gives fuel level, time and temp.

    We deal with traffic, we let the computer deal with fuel economy. It works for us.
     
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  6. elmo

    elmo Junior Member

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    the screen only.
     
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  7. bisco

    bisco cookie crumbler

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    it might be worth calculating at the pump and keeping a record
     
  8. elmo

    elmo Junior Member

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    it seems rjdriver was on the money when he suggested that low refrigerant might b making the compressor work hard and, as a result, rob the engine of some mpg's. been running the prius c without ac for about 10 miles in the ev mode and the mpg's are rising steadily. in the low 40's now and prob will let it go till I reach 45 mpg. then, will prob get my mechanic to give the car a charge so we can get back to running the air. in florida, its a necessity. thanks to you all for your insights, especially rjdriver.
     
  9. rjdriver

    rjdriver Active Member

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    Thanks for the praise Elmo, but that was Leadfoot who mentioned the low refrigerant as a possible cause.
     
  10. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Might not even be a low refrigerant situation. There is such a thing as a day hot enough to completely tank your mpg through cooling demand, even on a healthy system. You may have just found a string of those days that you weren't used to.

    Either way it sounds like you've discovered where the energy is going. Now to work out whether it was appropriate for your travel conditions, or if the system has gone low.

    Given a 10+ year old car, I'd probably spend the $80-90 for a "system checkout" at an independent automotive AC shop.
     
  11. elmo

    elmo Junior Member

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    thanks rjdriver for the correction. leadfoot b the man on pt. thank you. so far so good with gains with mpg and no ac. have an appt with mechanic(trusted) to work on the ac on 6/19. had a can of 134a and a gauge and tried to give the car a bit of a charge. gauge showed overage. prob not accurate so I opted for a mechanic. take care all.
     
  12. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Ah, in that case you now know that the refrigerant in there is the wrong amount. These are sensitive systems, and having the wrong amount of refrigerant (high or low) by just a few grams can really knock it out of kilter.

    If you've blindly added some, the right move would be to have all of it removed/recycled and then pay somebody to refill it with precisely the right amount.
     
  13. elmo

    elmo Junior Member

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    thanks leadfoot