an electrochemical fuel cell system adapted for maintaining the efficient production of electrical power . the system comprises a fuel supply containing a hydrogen rich gaseous fuel for delivery to a fuel cell . a fuel supply conduit connects the fuel supply and the fuel cell for delivering a fuel stream of the hydrogen rich gaseous fuel to the fuel cell . an impurity sensor is carried by the fuel supply conduit for detecting impurities in the fuel stream prior to the impurities entering the fuel cell . a heating mechanism is provided in communication with the impurity sensor being operatively associated with the fuel cell for changing the temperature of the fuel cell . the heating mechanism raises the temperature of the fuel cell from a normal operating temperature to an elevated operating temperature when the impurity sensor detects impurities in the fuel stream to prevent the impurities from interfering with fuel cell efficiency .