A measuring system and a method for operating it to detect wire breakage based on the measured current or voltage in which the impedance of at least a first sensor is measured and the result transmitted to a connected system. The invention is capable of detecting wire breakage and sensor failure in temperature sensor systems simultaneous with the temperature measurement by the measuring system comprising an AC current source which generates an AC current that is transmitted through the wires, and through at least the first sensor, measuring system analyzing changes in the phase angle between the current and voltage of the AC signal. If the difference in the frequency of the signal affecting the impedance or voltage of the sensor, and the frequency of the injected wire testing signal is sufficiently high, it is possible to distinguish between the first measuring signals and the second wire testing signal.