What a Flame Sensor Is and Why It Matters Published on February 26, 2017 Receiving your seasonal furnace maintenance helps keep your furnace operating up to 30% more efficient and helps extend the life of your system. But things may still malfunction, and when they do, you may feel like you’re always hearing about something else. This time it’s your motor, next time it’s your pressure switch. Now you have to have your flame sensor replaced. What is a flame sensor, anyway? A flame sensor is an important safety component on your gas heating system. During the ignition cycle, your gas furnace enters a process where a spark or a hot surface ignitor will ignite the gas. Once the gas is ignited, the flame sensor creates a current of electricity. The electricity is measured in micro amps. If the furnace’s control board fails to read the correct level of micro amps, the furnace will stop giving the system fuel to avoid an explosion. Over time, if the flame sensor is not cleaned appropriately, oxidation or carbon buildup can impede the flame sensor’s ability to function properly, which can result in a malfunction of the furnace. The way to determine if a soiled flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert heating technician can provide you. If a dirty flame sensor is the reason, the heating expert will clean the sensor with steel wool. If dirt was the sole factor, we will see a much higher amp reading. If the reading does not change, the technician will proceed with the heating system repair diagnostic process. If you aren’t sure your furnace is going to make it through these last few weeks of winter, give Service Experts Heating & Air Conditioning a call and we’ll come out and provide you with a full furnace maintenance or a complimentary in-home estimate on a new heating system.