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Gas Mileage decreasing

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by MickeyR, Mar 9, 2018.

  1. MickeyR

    MickeyR New Member

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    I have a 2010 with about 45k miles. I used to average about 48 mpg, but in the last year it's been slowly declining. I'm lucky to get 42 now. Even when the battery charge is full, I sometimes hear the engine start to rev. Even though I don't have a lot of miles, the battery is obviously almost 9 years old. Do I need a new battery or could it be something else?
     
    #1 MickeyR, Mar 9, 2018
  2. Lucifer

    Lucifer Senior Member

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    Traction or 12v
    12v definitly, Traction, well, a new one would be five years of like new mpg's
     
    #2 Lucifer, Mar 9, 2018
  3. bisco

    bisco cookie crumbler

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    welcome!
    could be a lot of things. how is the tires pressure, air filter and oil level? do you folks get reformulated winter gas?
    on the plus side, your hybrid battery has 3 more years of warranty.
     
    #3 bisco, Mar 9, 2018
  4. MickeyR

    MickeyR New Member

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    Thanks for the reply. I have been having issues with my tire pressure. I keep having to put air in, though the tires are fairly new. Filters/oil should be fine. I get them checked regularly. I live in Southern California so we don't deal with winter gas.
     
    #4 MickeyR, Mar 11, 2018
  5. MickeyR

    MickeyR New Member

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    thanks
     
    #5 MickeyR, Mar 11, 2018
  6. bisco

    bisco cookie crumbler

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    the tires need to be reseated, it sounds like. unlikely all the valves are leaking. who installed them?

    i also agree with lucy above, potential problem for a low mile battery.
     
    #6 bisco, Mar 11, 2018
    Last edited: Mar 11, 2018
  7. Sam Spade

    Sam Spade Senior Member

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    Get them checked at a DIFFERENT place once.
    Especially the air filter.

    There also is a filter for the battery cooling fan.
    Give it a dose of Techron.

    A 3 MPG change might be due to an aging HV battery.....but if it still has the original 12 V battery, THAT is due for a new one.

    And finally, if the tires continue to lose air, take it back to the place where they mounted the new tires and have them remove and RE-mount them and clean the inside of the rims like they should have done the first time.......unless maybe they find that the valve stems are leaking.
     
    #7 Sam Spade, Mar 11, 2018
  8. DavidA

    DavidA Prius owner since July 2009

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    Yes, new battery, absolutely needed. Most should be replaced at 5 years, or weird stuff begins to happen, like fobs not working.

    As for the mileage.... did you have the inverter recall done?
     
    #8 DavidA, Mar 13, 2018
  9. padroo

    padroo Senior Member

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    I had trouble with a slow leak after Costco changed my tires once. It was a leak around the TPMS sensor.
    They installed new stems and one wasn't done right.
     
    #9 padroo, Mar 14, 2018
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