How often should I test my gas furnace thermocouple?

The gas furnace thermocouple is a small component that sits next to the pilot light. If the pilot light is on, then the thermocouple sends an electric signal to the gas valve, instructing it to release gas. Alternatively, if the pilot light is off, then it acts as a safety mechanism, so that no gas is released. If your thermocouple is broken, then it starts instructing the gas valves to close even when the pilot light is on. It would be advisable to test your gas furnace thermocouple before the onset of winter, as this will be the peak period of usage, and after winter has ended, as the thermocouple may have received some wear and tear.