A self-diagnosing battery cell monitoring system having a battery cell voltage monitoring IC with a digital voltage substrate, an analog differential voltage substrate, and an analog voltage substrate is provided. The first diagnostic handler application commands a digital input-output device to generate control signals to transition a contactor to an open operational state if the first diagnostic flag associated with the digital voltage substrate is equal to the first encoded fault value, or the second diagnostic flag associated with the analog differential voltage substrate is equal to the second encoded fault value, or the third diagnostic flag associated with the analog voltage substrate is equal to the third encoded fault value.