Important Note about the Fuel Gauge Operation: The distance to empty (DTE) on GM trucks can’t be reprogrammed, so it will show about half the mileage that is really left. You can multiple the displayed range by 2 to find your actual range. The fuel gauge will operate properly. The fuel gauge will remain on full until about 4-5 gallons have been used and then the gauge will start to move normally. GM trucks monitor for an inoperative fuel gauge, so in some situations, until it starts to move, the truck’s computer will drop the gauge to empty to get the driver’s attention even though your tank is full. The gauge will return to its normal position after restarting the engine. We have seen cases when code P0463 appears due to the slow movement of the float, this can be cleared with a code reader. Once the fuel level drops 4-5 gallons from full, the fuel gauge will return to its normal operation The bottom of the S&B tank has more surface area than the OE, so there will be a greater fuel reserve when the low fuel indicator comes on. The nozzle at high-flow fuel stations(truck stops) will not be able to fill automatically. Do you have an Auxiliary Fuel Tank? Read why using these with our tanks will void the Lifetime Warranty.