We took our 2008 Prius in for a check engine light. The dealership said oxygen sensor was faulty. Changed that and had them change the serpentine belt while there due to cracks in the belt. My wife filled up the car the next day ( it took 13 gallons) but gas gauge was not registering a full tank. We drove 67 miles and I decided to pull in to a gas station and see how much it would take since the gas gauge was not working properly. It took over 7 gallons. What in the world is going on? I cannot see any fuel on the ground nor smell any gas.
Did you use same gas pump both times by chance? Are you sure you didn't go somewhere it was sold by the liter? Something is very wrong. The tank capacity of the Gen 2 Prius is 11.9 gallons. I've never been able to put more than ten gallons in mine.
We are in the U.S. so have not run into any stations that use liters. I will question my wife more about the trip to the station because I cannot find the debit on our bank account. Sometimes she gets confused and does not complete things. Looking into that now. Her fill up is not showing up on our bank account. She may have forgotten to activate the pump and was seeing 13 gallons from the previous customer's transaction. I will feel better if that is the case.
That would also let the station off from suspicion of fuel pump fraud. If she really did put in 13 gallons, I'd be checking with the state or county to have the pump calibration checked.