The present invention provides a microwave oven and a method of operating a microwave oven, which minimises user involvement when heating a food item to a desired target temperature. The clutch element has an internal toothing mating with the external toothing of the drive shaft and is shiftable together with the pinion shaft away from the starter motor in the axial direction of the drive shaft into a meshing position in which the pinion mates with a gear wheel or ring gear of the internal combustion engine. Comparable features for performing these steps are provided in the apparatus. The ghost value is calculated using a monotonous function of the distance between the non-ghost pixel of the binary map and the nearest ghost pixel. The resonant controller executes a corresponding protecting process in response to the protection signal. Having been fed with the compensated displacement value, the drive control portion varies the drive control value such that the compensated displacement value is equal to the target displacement value.