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Mileage declining at 23,000 miles

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by csk47, Jun 19, 2019.

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  1. csk47

    csk47 Junior Member

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    My 2016 Prius Two had been getting 54 mpg since we bought it until about three months ago. The car never leaves south Florida and I drive in the same traffic conditions on community roads every day. Now the mileage is down to about 44 mpg. I bought new tires recently but the drop was happening before then. It just seems that the battery level doesn't stay up as much as it did and the engine kicks on more. I am bringing it to the dealer next week for an oil change but I don't want to be sold work I don't need for the mileage problem which seems more batteries than gas engine to me. Do I need injector cleaning? Can they run some kind of a diagnostic check to show the cause? Any advice is greatly appreciated.
     
    #1 csk47, Jun 19, 2019
  2. jb in NE

    jb in NE Senior Member

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    The engine running more frequently and the battery level not staying up are totally unrelated to injector cleaning, which in any event should not be required at 23,000 miles.

    Note that if there is a problem with your hybrid battery or related control systems (ECU), this will be covered under warranty. Typically the dealer won't offer up warranty work first.
     
    #2 jb in NE, Jun 19, 2019
    Last edited: Jun 19, 2019
  3. bisco

    bisco cookie crumbler

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    at 23,000 miles, the only things it needs is oil and filter every 10k, air and cabin filters inspect/clean/replace at 30k and 15k respectively, tire rotation every 5k, and a bunch of inspections.

    are you tracking your mpg's manually calculated by the tankful at the pump?

    are you using the a/c a lot more?

    where did you buy it, are they reputable?

    why did you replace the tires so soon? what did you put on?

    what tires pressure are you running?

    the dealer can't help because you don't have any trouble lights on.

    check the 12v. a low 12v can reduce mpg. check the oil level too.
     
    #3 bisco, Jun 19, 2019
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  4. Fuel Miser

    Fuel Miser Junior Member

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    The big one I'd look at is the 12v battery. It is a common issue that when it begins to fail the mileage starts to suffer.
     
    #4 Fuel Miser, Jun 19, 2019
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  5. csk47

    csk47 Junior Member

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    I will check the oil level and have the dealer check the 12 v battery. Thanks for your help...
     
    #5 csk47, Jun 19, 2019
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  6. bisco

    bisco cookie crumbler

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    pleasure
     
    #6 bisco, Jun 19, 2019
  7. csk47

    csk47 Junior Member

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    I just checked my 12 volt battery that has been sitting overnight. The reading was 12.35 volts. That would indicate the battery is okay?
     
    #7 csk47, Jun 20, 2019
  8. bisco

    bisco cookie crumbler

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    borderline, but poly not the problem.

    at that voltage, i would swing by auto zone for a free load test. is it original?

    fyi, a new agm battery, fully charged is 13v.
     
    #8 bisco, Jun 20, 2019
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  9. csk47

    csk47 Junior Member

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    Yes, it is original. I find I get better help on this forum than calling the service "experts" at the dealership. Will go to Auto Zone. Thank you for your help.
     
    #9 csk47, Jun 20, 2019
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  10. Prodigyplace

    Prodigyplace Senior Member

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    Not on a 2016!
    I have more miles than that on my 2017 with no issues (approaching 30K)
     
    #10 Prodigyplace, Jun 20, 2019
  11. Prodigyplace

    Prodigyplace Senior Member

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    Gen 4 is not agm , but an unusual size.
     
    #11 Prodigyplace, Jun 20, 2019
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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Battery health depends on a lot of factors. A car seeing very light use is prone to have battery problems sooner.

    I suspect the designers have a checklist, and one item is to ensure the battery is rare or expensive, preferably both.
     
    #12 Mendel Leisk, Jun 20, 2019
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  13. bisco

    bisco cookie crumbler

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    sorry, i knew it was gen 4 in the beginning, but as it goes along, i keep spotting the 2010 in the vehicle data.:p

    12.35 is probably fine. still worth a load test, but i suspect another issue.

    problem is, on an almost new car, the usual suspects don't come into play.
     
    #13 bisco, Jun 20, 2019
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  14. Prodigyplace

    Prodigyplace Senior Member

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    Welcome to the club! :D
     
    #14 Prodigyplace, Jun 20, 2019
  15. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Any chance your A/C is working harder? Here in MS, we are in a season you see on your oven.
     
    #15 JimboPalmer, Jun 20, 2019
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  16. bisco

    bisco cookie crumbler

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    see post #4. come on jumbo, get with the program. you have to read the whole thread
     
    #16 bisco, Jun 20, 2019
  17. Prodigyplace

    Prodigyplace Senior Member

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    OK, 2 errors
    Post 3
    Jimbo
     
    #17 Prodigyplace, Jun 20, 2019
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  18. bisco

    bisco cookie crumbler

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    sorry teach!:cool:
     
    #18 bisco, Jun 20, 2019
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  19. Raytheeagle

    Raytheeagle Senior Member

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    Still one of the better auto corrects out there:p.
     
    #19 Raytheeagle, Jun 20, 2019
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  20. Prodigyplace

    Prodigyplace Senior Member

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    I wish I was as detail oriented in my typing. Programming languages are harsh critics.
     
    #20 Prodigyplace, Jun 21, 2019
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