CONTROLLER AND CONTROL METHOD FOR MULTI-CYLINDER INTERNAL COMBUSTION ENGINE

When an intake air amount is greater than or equal to the lower limit intake air amount and less than or equal to the upper limit intake air amount, a CPU sets, from the first cylinder group that increases a detection value of an upstream air-fuel ratio sensor, one of cylinders that has the smallest cutoff frequency, which is stored in a storage device, as a cylinder to which the supply of fuel will be cut off. Then, the CPU obtains the maximum value of an upstream air-fuel ratio as a maximum air-fuel ratio. When the maximum air-fuel ratio is greater than a determination value, the CPU determines that specific cylinder fuel cutoff control is normal. When the maximum air-fuel ratio is less than or equal to the determination value, the CPU determines that the specific cylinder fuel cutoff control is anomalous.