A carbon monoxide detector is an electronic device that senses the presence of carbon monoxide (CO) in a building and sounds an alarm to warn the occupants to escape. Carbon monoxide is an odorless, poisonous gas, which can be generated by gas furnaces and water heaters, ranges, space heaters, or wood stoves if they are malfunctioning or not vented properly. Cars, portable generators, and gas-powered gardening equipment also generate carbon monoxide and can cause problems if they are operated in enclosed areas or attached garages