How to troubleshoot a faulty gas furnace ignition or pilot light

If your furnace pilot doesn’t light up or remain lit, the main causes are generally;
a loose or faulty thermocouple, a clogged pilot orifice or the flame could be set lower than it should.

  • ist Turn off the gas to the furnace
  • Shut off the switch or circuit breaker that controls power to the furnace
  • Then try to clear the clogged orifice with a piece of thin wire and remove any debris.
  • Turn the flame adjustment screw to get a full, steady 1 and 1/2-inch to 2-inch flame with no yellow in it. You may need to refer to the furnace manual to complete this step.
  • Make sure the valve on the gas pipe is turned on in order to keep providing your furnace with gas.