Cylinder deactivation, also known as Active Fuel Management (AFM) or Variable Displacement, is a technology used to improve fuel efficiency and reduce emissions by shutting off a portion of the engines cylinders under light load conditions. In an F6 (flat six) engine design, this could mean deactivating one bank of three cylinders or alternating between individual cylinders across both banks. The engine control unit (ECU) manages this process by cutting fuel delivery and preventing valve operation for the deactivated cylinders, effectively turning the F6 into a smaller-capacity engine when full power is not needed.