Abstract: An activity monitor for a gas cooker or grill which monitors activity with a motion detector. When the grill has not been used for a preselected time period, the gas supply is automatically shut off to avoid fire hazard and/or wasting of fuel. An adjustable timer is used to activate the automatic shut off of the gas supply only after no motion has been detected for a preselected time period. A default timer value can be used when the grill is initially activated. If motion is detected prior to gas supply shut off, then the timer is reset to zero. Motion detection is accomplished by one or more methods including a lid position sensor to detect when the grill lid is moved between the open and the closed position a motion detector which monitors switch usage to detect activity, and vibration or movement monitors.