NOVELTY - Detecting a fault in an electrochemical cell module comprises determining operating characteristics of the electrochemical cell module for a discrete frequency to obtain a measured impedance value, providing a reference impedance value and a fault criterion and comparing the measured impedance value with a reference impedance value.    USE - Used for detecting a fault e.g. dehydration, flooding and catalyst poisoning in an electrochemical cell module.    ADVANTAGE - The process accurately determines the cause of a particular fault in an electrochemical cell based on an impedance measurement characterizing the electrochemical cell.    DETAILED DESCRIPTION - Detecting a fault in an electrochemical cell module comprises:    (1) determining operating characteristics of the electrochemical cell module for at least one discrete frequency to obtain measured impedance value;    (2) providing a reference impedance value and a fault criterion based on a deviation from the reference impedance value; and    (3) comparing the measured impedance value with a reference impedance value to determine whether or not the fault criterion has been satisfied.    An INDEPENDENT CLAIM is also included for a system for detecting a fault in an electrochemical cell module comprising:    (1) a sensor(s) connectable to an electrochemical cell module for monitoring at least one operating parameter of the electrochemical cell module; and    (2) a computer program product including a computer usable program code for determining whether or not at least one fault criterion has been satisfied and thus indicating the presence of a fault in an electrochemical cell module, the computer usable program code including program instructions for determining operating characteristics of the electrochemical cell module for at least one discrete frequency to obtain a measured impedance value, and comparing the measured impedance value with a reference impedance value and at least one fault criterion to determine whether or not the fault criterion has been satisfied.    DESCRIPTION OF DRAWING(S) - The flow chart illustrates the process of fault detection in an electrochemical cell.