A system and method for detecting an intermittent failure of an injector that injects hydrogen gas fuel into the anode side of a fuel cell stack in a fuel cell system. The method includes operating the injector at a fixed injector pulse width and frequency, which causes the stack to generate a constant current, and therefore, a constant fuel consumption rate. While at a constant current, the injector is commanded to a constant duty cycle and frequency that matches the rate of fuel consumption in the fuel cell system. The resulting fuel pressure feedback is then monitored, and if it diverges from a defined nominal value, either in a constant or oscillatory manner, it can be determined that the injector has an intermittent opening failure. In one embodiment, the determination of the injector failure is performed during a shut-down sequence of the fuel cell system.