A system is disclosed for monitoring the output of a gas ignition module used for controlling the heating of a cooking device, such as a deep fat fryer, in a pulsed heating mode. The system includes a controller which detects a failure in ignition and alerts the user of the cooking device of such a failure. In a preferred embodiment, an optoisolator is used to monitor the voltage applied to a gas valve. From this determination, the system logically determines when a gas lockout has occurred, and prevents successive ignition attempts, which could result in an unwanted accumulation of gas.