A trend towards measuring and monitoring all liquid levels in the automobile exists for a certain time already.This explains why the well-known fuel tank sending unit system has seen the development of other liquid switches. Today, these level switches show wide variations in size and measuring principle. Furthermore, these switches have been designed for a specific application in most cases, and they are not compatible with other ones.Starting on this basis, VDO developed a piezo level switch; this switch is independent of the measured fluid, sturdy, small, of modular design, and operates in a wide temperature range. A measuring system has been developed as well to eliminate the drawbacks of other known piezo systems. The possibility of scanning several sensors by an electronic module using the multiplexing technique has been taken into account.