With the increasing number of plug connections in products, which are proportionally less and less space consuming, the potential for device failure caused by defect connectors increases. Therefore, it will be increasingly important to ensure the proper functioning of the electrical connections. Within the framework of a research transfer project, sensors are being developed to test the contact normal force in sub-millimeter plug connectors. The basis of the sensors is the use of silicon based micro electro mechanical systems (MEMS), which act as mechanical-electrical converters. The presented test method is a further development of a technology published in 2015, with the background of the lifetime increase and an enhanced industrial usability. The number of measurement points was reduced to the resolution of contact point pairs. The measuring range of the contact normal force is 0.5 to 8 N for the realized sensors. An XYZTEC Condor Sigma and an adapted sensor unit have been used to record the mating force and the contact normal force of terminals with a 1.2 × 0.6 mm2 opening dimension.