I'd like to know because this morning the tank empty light was lit and I filled the van up as I usually do from the same place I always do. I always wait until the light comes on then fill it up. The pump has always told me that it took anywhere from between 17.5 to 19.5 gallons to fill up the tank. This morning the display read 20.89. It makes me wonder if the pump wasn't calibrated correctly accidently or even intentionally.