Carbon monoxide diffusion detector (CO) sensor for COsensor system designed according to the European standard EN 50545-1 and UNE 23300 certified. The sensor is designed to work with all models of COsensor plants, both conventional (CCO and MiniCO models) as addressable (ZafirCO). In this sense, the sensor, when the control panel is turned on, recognizes the model and adapts its communication to that required by it. The detector sensor is based on electrochemical technology that allows it to respond appropriately to CO concentrations in the environment, and send this information to the plant. In this way the plant will act appropriately, activating the necessary ventilation and alarms.