... working properly, perhaps due to poor installation, lack of regular servicing or a chimney/flue blockage. CO ... danger signs? For you, these could be the first signs of CO poisoning : If you feel drowsy, overtired, ... deposits or is burning yellow/orange or smells of fumes/tends to go out have the appliance ... Carbon Monoxide Detector is activated by the presence of CO, the alarm will imediately sound. It ...