Unlike older pilot lights, which have to be lit by hand, automatic pilot lights, commonly found in home furnaces, are regulated by a thermostat and only ignite when needed. While older pilots burnt constantly, wasting gas, automatic pilot lights come on long enough to ignite the gas supply and then shut off. Since automatic pilot lights can not be lit by hand, the procedure for lighting them is entirely different. To light an automatic pilot light you must shut off the gas supply, effectively resetting the system and relighting the pilot. No tools are needed to relight the pilot.
Set the thermostat on your furnace to its lowest setting. Shut off all electrical power to the furnace, either by using the "Off" switch on the furnace or by flipping off the circuit breaker in your house.
Remove the access panel covering the gas control knob. Typically this will be found toward the bottom of your furnace.
Turn the gas control knob to the "Off" position. Certain furnaces may have two gas control knobs. If that is the case, turn them both to the "Off" position. Wait five to 10 minutes for any residual gas to clear out of the furnace.
Turn the gas control knob or knobs to the "On" position. Replace the access panel.
Turn the electrical power to the furnace back on. Set your thermostat to your desired temperature. After a few seconds the pilot will light up, igniting the furnace's burners.
If you smell gas at any point or if you are unable to get the furnace to light using this technique, stop working on your furnace and call a repair service.