Fuel anti-theft systems, apparatus, and methods. Embodiments provide fuel anti-theft systems including a circuit and sensors which define nominal (secure) and tampered-with states. The tampered-with states are indicative of the sensor(s) being absent. Controllers of the current embodiment, moreover, senses a combined state of (all of a pre-selected number of) the sensors and determines therefrom whether all of the sensors are present and secure. In some embodiments, the controller senses the sensors (which can be wired in parallel) via a vehicle chassis ground. If desired, a resistor (which is about electrically equivalent to one of the sensors) and/or a geo-positioning system can be connected to the controller. The sensors can include normally open switches and clamps, cable ties, adhesives, etc. which close the switches. Some sensors include grounding straps while others include ground return leads. In some embodiments, sensors are positioned at vehicle fuel caps and/or fuel filters.