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.
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.
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.
