How to Relight a Furnace Pilot Light

The furnace stopped making heat and the advice everywhere is to relight the pilot. On most furnaces there is nothing to relight. Anything built since the mid 1990s almost certainly uses electronic ignition and has no standing pilot at all, so hunting for a small blue flame behind the burner panel is how an evening gets wasted.

Confirm the furnace actually has a standing pilot

Look at the gas valve, the block the gas line runs into. A dial marked Off, Pilot, and On, with a small tube running from the valve toward the burners and a red or black reset button nearby, means a standing pilot. A control board with wiring, a display or blinking LED, and either a glowing ceramic igniter or a sparking electrode means electronic ignition. Electronic ignition has no pilot, and a no heat call there is a different problem entirely.

Cut power at the furnace service switch

Flip the switch that looks like a light switch on or near the unit before removing the burner access panel.

Turn the gas dial to Off and wait five full minutes

This is the step people skip, and it is the one that matters. Five minutes lets any unburned gas in the burner compartment clear before a flame goes anywhere near it. Watch a clock rather than guessing. If gas is still noticeable in the air after that, stop and go outside.

Set the dial to Pilot and light the pilot tube

Turn the dial to Pilot, press the reset button down and hold it, and bring a long stem lighter to the end of the pilot tube. The flame should catch and sit steady against the tube.

Hold the reset button for 30 to 60 seconds

Keep holding after the pilot lights. The thermocouple beside the flame needs to heat up before it will generate enough current to tell the valve the pilot is burning. Release too early and the flame goes out. Once it holds on its own, turn the dial to On, replace the panel, and restore power.

If the pilot lights and dies every time. The thermocouple or thermopile is the usual cause, and it is an inexpensive part. Replacing it means working at the gas valve, which is a call worth making to a licensed HVAC technician rather than a first project.

If gas is noticeable at any point. Leave the building immediately. Do not flip switches, do not use a phone indoors, and do not try again. Call the gas utility or 911 from outside and let them clear the house first.