Were you 37 gallons low ?
Propane is dispensed by the gallon in fixed tanks.
Find the tank and look for the gauge on the side. It will be one of two types. With screws or snap in. Both will have wires leading to the internal indicator.
Look at the needle on the gauge and see if its readinf full. If it is, check the wiring going to it.
If its bad, it can be changed by snapping it out or removing the tiny screws on the plastic part. No gas leaks.
Here is what it looks like. They are not showing the wires.