This paper presents a new approach based on a watchdog infrastructure intellectual property (I-IP) core to detect control-flow faults that affect CPU execution time. More precisely, this approach aims at detecting those faults that change the expected CPU instruction sequence and that as consequence, change also (by increasing or reducing) the expected CPU time allocated for the execution of the monitored task. The underlined advantage of this approach is the ability of detecting faults in systems-on-chips (SoCs) simultaneously running multiple tasks under the control of a real-time (preemptive) operating system (OS). In this multi-task scenario, the I-IP performs fault detection in a time-shared basis. Practical experiments based on the IEC 62.132-2 Std. for IC electromagnetic immunity measurement have been carried out and the obtained results are discussed.