The fuel level sensor is the sensor located in the fuel tank that tells the vehicle how much fuel is in the fuel tank. This sensor has a float attached to it that may become wedged against the fuel tank, causing the float to be stuck in one spot instead of "floating" on top of the fuel in the tank. Because the float can not move, the instrument cluster will indicate that the fuel level is still full, even though it empty. Running the vehicle out of fuel will result in the vehicle shutting off (stalling) while driving down the road. BMW will replace the fuel level sensor free of charge. If you own a 2010 or 2011 5-series and did not receive a notice, contact BMW at 1-800-525-7417 or the national highway traffic Safety Administration at 1-888-327-4236 to verify this recall does not apply to your vehicle. You may need the Vehicle Identification Number (VIN), located on a placard attached to the vehicle's driver side door frame. Your vehicles production date is also on this placard.