A system and method for providing fault detection capability is provided which comprises a first node (2). The first node (2) comprises a first processing subsystem (5) generating data (14) to be transmitted. The first node (2) has a fault supervisor unit (13) adapted to gather and process fault indications arising in the first node (2). The first processing subsystem (5) and the fault supervisor unit are both integrated in the first node (2). The first node (2) is structured such that, when no fault indications are detected by the fault supervisor unit (13), the fault supervisor unit (13) provides a first key (15) as a validity key, and, when at least one fault indication is detected by the fault supervisor unit (13), the fault supervisor unit (13) provides a second key (16) as the validity key, and the data (14) to be transmitted are encrypted by overlaying the respective validity key (15; 16) on the data.