The biggest sign that your thermocouple is bad on your furnace is if your pilot will light, but does not remain lit. If your pilot light is lighting, but not staying lit, you can attempt to clean the pilot tube. If everything is clear of obstructions and your thermocouple is still not working properly, you should have an experienced HVAC technician inspect and repair your furnace for you. To find out more about getting your furnace repaired, give us a call today.