A method and system for detecting flame rollout is disclosed. The detection system includes a processor programmed to execute a furnace lockout when the flame proving signal is lost three times after successful burner ignition has been established on each of three heating cycles within a predetermined period of accumulated burner on-time. In one embodiment the period of accumulated burner on-time is 60 minutes. The program executed by the processor resides in firmware. The system and method of present invention mitigates the potentially harmful accumulation of flue gasses when flame sense is lost due to flame rollout.