Gas Gauge seems faulty

I've been letting my wife drive the 2007 Prius since I've been cycling in to work. I got in the car last night and thought "Wow, almost a full tank". I then realized that only 1 pip was missing for 208 miles! The MFD was reading average mpg around 43, so this was bizarre. Usually the first pip drops around 110-120 miles.

By the time we got back home, I was around 220+ and 2 pips were gone. This is usually when half the pips are gone. Is this something I should be concerned about? Should I reset the gauge? I don't want to mess with something that doesn't need to be messed with.

Thanks in advance.

 

Thank you, I am aware of this. I bought the car brand new in 2007 and spent quite a bit of time on this forum until I disappeared into the night.

I've never ever had a fluctuation like this. I've had the car in very hot (100+) and very cold (Teens/Snow) and never had this issue before. On average (I've tracked every tank), I get anywhere between 390-430 miles on a regular basis and my gallons per fillip has always been within 1 gallon of each other. My concern is that I (or my wife) will rely on the gauge thinking we have gas left, but in actuality have very little gas and thus run out.

 

So drastic, so sudden? Alright, I'll keep my eye on it and see.

 

Thanks. This is exactly what I did. After a few tanks, it seems to have gone back to 'normal'. I'm not sure how my wife crammed in 11.6 gallons in the tank before this, but it appears that was the 'issue'.

Thanks for all of the help, everyone!