Furnace hot surface igniter (HSI)

Furnace HSIs are silicon carbide or silicon nitride elements. Measure cold resistance against the type; replace if open or far out of range. Handle only by the base.

Cross-checked ~25 min moderateBrands: All

Before you start

Turn off power and gas at the appliance valve before removing the igniter
Never touch the element; skin oils shorten life
Gas valve work is blocked; refer

Diagnostic steps

Unlock all 3 steps with expected values

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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