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2007 Prius mileage going down, down.

Discussion in 'Gen 2 Prius Fuel Economy' started by muirallen, Dec 7, 2011.

  1. muirallen

    muirallen Greyman

    Joined:
    Mar 15, 2008
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    Location:
    Saint Augustine, FL
    Vehicle:
    2007 Prius
    Model:
    II
    We have a garden variety 2007 basic Prius. That description will tell you that I'm no Mechanic.
    The mileage was between 40 and 43 MPG for years. Now it has suddenly dropped to 33 and 35. The average temp here in Florida is fairly consistent at above 60 F, so that is not it. Oil changed at the dealer, and not overfilled. Tires at the right pressure. Worn to perhaps 50% of their avg tread life. Also, I had the 12 Volt battery replaced at the dealer a few months ago, and no change.
    Any ideas out there about this being a possible programming problem? is there a way to check?
    Thank you, and Happy Holidays to all!
     
    #1 muirallen, Dec 7, 2011
  2. xpcman

    xpcman Senior Member

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    Location:
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    Vehicle:
    2008 Prius
    You can disconnect the 12V battery for a few minutes and that will erase the computers memory. That has helped a few Priuschat members. I had this problem last year and it turned out to be overfilled and wrong type oil - since the problem went away at the new oil change.
     
    #2 xpcman, Dec 7, 2011
    1 person likes this.
  3. cwerdna

    cwerdna Senior Member

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    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    #3 cwerdna, Dec 7, 2011
  4. muirallen

    muirallen Greyman

    Joined:
    Mar 15, 2008
    4
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    0
    Location:
    Saint Augustine, FL
    Vehicle:
    2007 Prius
    Model:
    II
    Is there any bad side to erasing the computers memory? Like "Automotive Amnesia"? I know you probably would not tell someone to try it if you new that it would be a problem, and thank you for responding. I am going to check the oil again on a level surface. (may have been in our garage, which has a minor grade)
    Also, do you have a tire pressure recommendation?
    Thanks again.
     
    #4 muirallen, Dec 8, 2011
  5. F8L

    F8L Protecting Habitat & AG Lands

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    Aug 14, 2006
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    Location:
    Grass Valley, CA.
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    There is no bad side to refreshing the ECU.

    Tire pressure depends on what your tires max rating is. Most people find a happy medium between comfort and mpg using a 44/42psi setting. That is assuming your tires are rated at 44psi max.
     
    #5 F8L, Dec 8, 2011
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