Abstract: An improved liquid level measuring apparatus having a plurality of spaced reed switches having a microprocessor attached to the liquid level measuring sensor apparatus. The switches are wired together in parallel and in sets and are addressed by a shift register for providing a parallel to serial shift of the switch status position to the microprocessor. This allows a reduction in the number of conductors existing the sensor and providing an output signal indicating the vertical position of a float relative to the switches. A microprocessor control notes any inoperative switches, disregards the reading of the inoperative switches in calculating liquid level, and provides stored information to the measurement process for compensating for defective switches.