A controller may have a plurality of self-diagnostic functions, each of which is configured for checking a function of an assigned hardware component of the controller. Each of the self-diagnostic functions may have at least one safety limit value, which is configured such that when the at least one safety limit value is exceeded the corresponding hardware component is switched off. Each of the self-diagnostic functions may have at least one quality limit value, the absolute value of which is smaller than an absolute value of the at least one safety limit value. The at least one quality limit value can be configured such that a quality-relevant state can be detected in the assigned hardware component when the at least one quality limit value is exceeded.