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gas bars show zero but the tank's full

Discussion in 'Gen 2 Prius Main Forum' started by thelouvre, Jul 22, 2012.

  1. thelouvre

    thelouvre New Member

    Joined:
    Nov 11, 2008
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    Location:
    Austin, Tx
    Vehicle:
    2009 Prius
    We just got through changing out the 12 volt battery. Car is 2009 and had 60k miles but last summer was a killer hot summer in Texas. The care was doing strange things with the first start of the day with the triangle! coming on and then having to turn off the car and power back on to get it to go. So all posts seemed to indicate bad battery. We checked diagnostics and it was showing 9 volts. So now it is changed, diagnostics shows 12 volts but the gas indicator went to nothing. no bars. yesterday it was all bars. I supposed someone could have siphoned off all my gas last night but highly unlikely and too coincidental that it shows that after the battery change. Is there something we need to reset?

    Sorry if this is not the correct forum. Couldn't find a start new thread in trouble shooting.
     
    #1 thelouvre, Jul 22, 2012
  2. nh7o

    nh7o Off grid since 1980

    Joined:
    Dec 10, 2011
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    Location:
    Hawaii
    Vehicle:
    2009 Prius
    Model:
    II
    I'll offer this:
    Fuel Gauge Calibration Instructions | PriusChat

    The fuel gauge is notorious for inaccuracy. The above might have some relevance, but it seems to apply more to gauges that are only somewhat off. The only other thing that comes to mind is that the fuel level sender is not working, but that would be very coincidental to fail after a 12V change. It is also very difficult to get at the wires to make a voltage check directly, so that would be a last resort.
     
    #2 nh7o, Jul 23, 2012
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
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    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    After the 12V battery is replaced, it takes a short while for the fuel gauge to register the proper fuel level. If you should find that the gauge remains incorrect, try disconnecting the 12V battery negative cable where it attaches to the body for a few minutes, then reconnect the cable. The point of doing that is to give the fuel gauge circuitry another chance to reset itself.

    If that doesn't work then I suggest you seek dealer service department help.
     
    #3 Patrick Wong, Jul 23, 2012
    dave77 likes this.
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