Abstract: A system for monitoring fuel level in a fuel tank including a wireless tank sensor unit and wireless receiver unit pairing. The wireless tank sensor unit is mountable to a fuel tank and interacts with the installed fuel level gauge assembly and operates to transmit fuel level data to the wireless receiver unit installable in a remote location in radio frequency (RF) range of the wireless tank sensor unit. The wireless receiver unit operates to process the received fuel level data and provide, responsive to fuel level data exceeding user-defined thresholds, notifications corresponding to actions to be taken corresponding to a refill event. In some embodiments, the system may further include a mobile application installable on a portable electronic device. The system may operate in an internet-connected mode or an internet-disconnected mode based on user preference and/or availability of an internet connection.