The activation of programmed sequences to be executed iteratively is monitored by the sequences themselves. Each monitoring program sequence includes the additional function of monitoring at least one other sequence. The sequences can be in the form of routines, e.g. interrupt routines, and main program loops normally implemented in a programmed system. For instance, each programmed sequence performs the monitoring function by incrementing a value in a respective counter associated with each programmed sequence it monitors and by checking, for each counter, that the corresponding value has not reached a predetermined threshold. Each monitored programmed sequence resets the counter associated therewith. A failure in the activation of a particular programmed sequence is detected when a counter associated with that sequence reaches a predetermine threshold. The invention also relates to a computer program and a programmed apparatus implementing this concept.