A flame sensor is a vital safety device located near the burner of a gas furnace that detects the presence of a pilot or burner flame. It works by using a small electrical current to "sense" the fire; if the flame goes out but the gas keeps flowing, the sensor immediately signals the Control Board to shut off the gas valve. This prevents dangerous gas buildup and potential explosions in Mobile Home Gas Furnaces. Over time, carbon deposits can build up on the sensor rod, causing it to malfunction and "nuisance trip" the system. You can find replacement sensors and cleaning supplies in our Parts department. Most ACIq furnaces feature easily accessible sensors to simplify annual maintenance. Keeping this part clean is one of the most effective ways to ensure your Ducted heating system remains reliable all winter long. It is the primary electronic watchdog for the combustion process.