Function monitor

A function monitor (1) for a system (2) , such as an advanced driver assistance system (2), comprising a first function monitor element (3) and a second function monitor element (4), said first function monitor element (3) configured to receive and collate sensor data from a plurality of sensors (5a-5e) associated with the system (2) and send a function warning signal to said second function monitor element (4) when said sensor data from one or more of the plurality of sensors (5a-5e) is indicative of a functional irregularity.