We moved into a house in March of last year, and the house is at/around the 20 year mark. During that time the furnace kept kicking on and would then kick off again a few moments later, but I didnt think much of it as we were coming up on spring and I had no experience with a gas furnace. Fast forward to October when we turned the heat back on, and the furnace kept doing the same thing. One of our friends who does heating and air came out and replaced the flame sensor, and weve had no problems with the furnace for the rest of the fall and winter until a few weeks ago. Then the furnace started doing the same thing where it would run for a little bit and then the flame would kick off. My friend came out and showed me how to pull the flame sensor and kind of scrape it off and then wiggle the connections to the circuit board in case it did it again. In the past week Ive had to do this about four times, and I notice there is a kind of carbon build up on the sensor every time I pull it. My question is this; shouldnt a flame sensor last longer than a season, or is this a part that needs to be replaced yearly? Or, could it be possible that the replacement sensor he installed last fall was a dud? Thanks in advance.