The authors’ work deals with modelling with coloured Petri nets (CPN) of network controlled systems (NCS) and exposes a proposal of a sensor fault detection and prevention mechanism. In NCS, the network must be viewed as part of the system and not just a means of communication. For this, two issues must be considered. The first consists of adapting the control and diagnostic laws to the performance of the network. The second is to guarantee the performance of the system. Each control loop containing a network is vulnerable to faults and cyber attacks and malicious users can intercept and listen to data during transmission. For that reason, it is essential to protect transmitted data against unauthorized access and modification and to diagnose components. In this paper, the authors presented a model with CPN of a NCS, the authors proposed a sensor fault detection and correction mechanism, then the authors injected a sensor fault and the authors tested the effectiveness of the proposed mechanism in detecting that fault and correcting its influence. Simulation results proved the success of the preventive mechanism in overcoming the influence of the fault and returning to normal behaviour.