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How do you replace a furnace hot surface igniter?

Updated August 2026

30–45 minutes · Moderate DIY

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Two screws, one plug, and a $15 to $50 part: replacing a hot surface igniter takes 30 to 45 minutes, and no gas fittings come apart. The igniter is a brittle ceramic element that glows to roughly 2,000°F to light the burners, and it fails every 3 to 5 years on average, usually on the first genuinely cold night. Confirm the diagnosis before you order, match the element type, and never touch the new one with bare fingers.

What you need

Before you start: This is gas equipment and it deserves the full routine. Kill power at both the service switch and the breaker, close the gas valve while you work, and let the compartment cool 15 minutes. Never jump the door interlock switch to watch the burners with the panel off. If you smell gas at any point, leave the house and call the gas utility from outside, and do not flip switches on the way. Two findings mean stop and hire a pro: soot or lazy yellow flames on the burners, and a new igniter that fails within weeks, which points at a control board, a voltage problem, or a cracked heat exchanger.

Steps

  1. Confirm the diagnosis. Watch a heat call through the sight glass: the inducer spins, the pressure switch clicks, and the igniter should glow bright orange within 20 to 45 seconds. No glow and no flame points at the igniter or its circuit.
  2. Cut power at the furnace service switch and the breaker, then close the gas shutoff on the pipe to the furnace. The handle sits perpendicular to the pipe when closed.
  3. Wait 15 minutes. A hot surface igniter operates between 1,800 and 2,500°F and holds heat long after the burners stop.
  4. Photograph the igniter in place, including bracket position and wire routing, then unplug the two-wire connector from the harness.
  5. Back out the one or two 1/4 inch hex screws on the bracket and pull the igniter straight back out of the burner box. Do not lever it or let the element tap sheet metal, because it snaps like a cracker.
  6. Match the replacement to the old part. Silicon nitride igniters are flat spade-shaped elements; silicon carbide igniters are the fragile M-shaped or spiral kind. Use the OEM number where you can, or a universal kit that ships with the right bracket and adapter.
  7. Handle the new element by its ceramic base or with clean gloves only. Skin oil bakes into a hot spot and can cut years off the part.
  8. Mount it in the original position, plug in the connector, and close the burner door completely so the interlock switch is pressed.
  9. Open the gas, restore power, and watch a full cycle: glow within 45 seconds, burners lighting across the row, and flame holding past 10 seconds.

Or hire it out

A pro charges $150 to $400 to replace a hot surface igniter, and an after-hours or holiday visit adds $100 to $250 on top. The part is $15 to $50 and the failure reliably picks the coldest night of the year, which is why plenty of people keep a spare taped inside the furnace cabinet.

Done. Now the part everyone skips: doing it again on schedule. Log it in OnOtto and the next reminder for furnace igniter swaps sets itself.

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Frequently asked questions

Is it the igniter or the flame sensor?

Watch what happens after the inducer runs. No glow and no flame means the igniter side. A glow, then burners that light and die a few seconds later, means the flame sensor is not proving the flame, and that one is a cleaning rather than a part. A furnace igniter that will not glow covers the circuit checks, and cleaning the flame sensor is the 20 minute alternative if the burners do light.

Can I test the old igniter with a multimeter?

Yes, with power off and the connector unplugged. Set the meter to ohms across the two pins: a silicon carbide igniter typically reads somewhere in the 40 to 90 ohm range cold, and silicon nitride parts read lower, so check the spec for your part number. The extreme is what matters most. An open circuit, shown as OL, means the element is cracked through and dead, and a visible hairline crack in the ceramic tells you the same thing without a meter.

Why do igniters keep burning out?

Three to five years is normal life, because the element cycles from room temperature to 2,000°F several times an hour all winter. Faster failures usually trace to short-cycling from a clogged filter or an oversized furnace, line voltage running high, or someone handling the element bare-handed. If you replace one every season, have the cycle rate and voltage checked. Replacement intervals and igniter lifespan have the details.

Universal kit or the exact OEM part?

OEM when the price gap is small, since the bracket geometry positions the element precisely in the flame path and a millimeter matters. Universal kits work well if they include the correct mounting bracket and connector, and they are often the only thing available same-day on a Sunday. Do not substitute a carbide element for a nitride one without checking that the control board supports it. What a furnace igniter is explains the two types.

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