OEM Lennox Hot Surface Ignitor — 25N40

The genuine OEM Lennox 25N40 hot surface ignitor is a precision-engineered component that heats to extreme temperatures to ignite the gas burners in your Lennox furnace. Each ignition cycle relies on this part to glow hot and light the burner reliably, making it one of the most critical components in your heating system. Designed as a direct factory replacement, it ensures correct fit, resistance, and heat-up timing for your Lennox equipment.

Common failure symptoms include a furnace that blows cold air, fails to ignite, short-cycles, or displays an ignition-failure fault code. Hot surface ignitors are fragile and naturally degrade over repeated heating cycles, developing hairline cracks or losing the ability to reach ignition temperature. A visibly cracked or discolored ignitor is a clear sign the part needs replacing.

Why OEM matters: aftermarket universal ignitors often have mismatched resistance values and mounting geometry that can cause delayed ignition, rollout, or premature failure. The OEM Lennox 25N40 is built to factory specifications for guaranteed compatibility, proper flame timing, and long service life in your Lennox furnace.