A software code operates with a circuit interrupting device having an auto-monitoring circuit including a controller for automatically testing various functions and structures of the device. The auto-monitoring circuit initiates the software code which includes an auto-monitoring routine which, among other things, establishes a self-test fault during the positive or negative half-wave of an AC power cycle and determines whether the detection mechanisms within the device properly detect the self-test fault. Moreover, the software code executed by the controller compares sensed voltages from test signals with a determined or set maximum voltage value and compares the sensed voltages with a set or determined minimum voltage value. The sensed voltages must be greater than the maximum voltage value or lower than the minimum voltage value for a predetermined number of counts before an end-of-life state is determined for the circuit interrupting device. The number of counts reduces the likelihood of false detections of error conditions by the auto-monitoring circuit when determining whether the circuit interrupting device has reached the end of its useful life.