How to Replace a Furnace Igniter

Igniters are the unsung heroes of your heating system. When your furnace clicks but fails to ignite, it is almost always because the silicon carbide or silicon nitride element has reached the end of its life cycle. It is a brittle part that breaks down under the intense heat cycles it undergoes every winter, but replacing it is a straightforward task that gets your heat back on in under an hour. Successfully replacing an igniter requires a steady hand and a calm approach. You are dealing with delicate components and electrical connections, so patience is your best tool. Done well, this repair saves you a significant service fee and restores your home to comfort without the need for specialized HVAC diagnostic equipment.

  1. Kill the Power First. Locate the power switch on the side of the furnace or flip the circuit breaker in your electrical panel. Never attempt this repair with power active, as the igniter circuit remains live even when the thermostat is off.
  2. Open the Furnace Access. Remove the front access panel of your furnace. Most modern units are held on by thumbscrews or quarter-turn fasteners, though some require a standard nut driver.
  3. Find the Failing Igniter. Look for a small, fragile-looking component mounted near the burners, usually connected by a white or black porcelain-shielded wire. Do not touch the heating element of the old igniter, as oils from your skin can cause it to fail prematurely.
  4. Unplug the Igniter. Follow the igniter wire to the furnace's control board or the main wire harness. Unplug the plastic molex connector by squeezing the locking tab; do not pull by the wires themselves.
  5. Unscrew the Old Element. Use a nut driver to remove the single screw holding the igniter bracket in place. Carefully slide the igniter out of the burner box, ensuring you do not bump the fragile element against the metal burner housing.
  6. Seat and Secure New Igniter. Slide the new igniter into the housing, aligning the mounting hole with the bracket. Secure the screw firmly, then plug the connector back into the harness until it clicks.
  7. Confirm Heat Is Back. Replace the furnace panels and restore power. Set your thermostat to call for heat and observe the furnace cycle to ensure the igniter glows orange and the burners light promptly.