Lennox E207 Error Code

What does Lennox E207 mean?

E207 means the IFC has sensed an open circuit in the hot surface ignitor (HSI) circuit. The board monitors ignitor resistance during the pre-ignition warm-up period; if the ignitor reads open — indicating a broken element — it logs E207 and halts the ignition sequence. The SureLight silicon nitride ignitor used in the SL280DFNV should measure 39–70 ohms at room temperature; readings outside that range or an open circuit require replacement.

Symptoms

• Furnace begins the heating sequence — inducer runs — but no glow is visible at the ignitor.
• E207 alert on thermostat or control board; no heat produced.
• Furnace may attempt one or two cycles before entering a lockout.
• Cracked or visibly fractured ignitor element found on inspection.

Common causes

• Worn or cracked hot surface ignitor element that has reached end of life (typically 3–5 years).
• Physical damage to the ignitor from mishandling during a prior service call — touching the ceramic element with bare hands deposits oils that cause premature failure.
• Open circuit in the ignitor wiring harness between the IFC and the ignitor.
• Ignitor vibrated loose from its mounting bracket, causing an intermittent open circuit.

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Diagnostic steps

1. Power down before inspecting the ignitor

   Turn off the furnace disconnect and verify zero voltage. Allow the furnace to cool if it has recently attempted to fire — the ignitor reaches over 2000°F during operation.

2. Measure ignitor resistance

   Disconnect the ignitor leads and measure resistance with a digital multimeter set to the 200-ohm range. A reading of 39–70 ohms indicates a functional ignitor; OL (open loop) confirms the element is broken.

3. Inspect ignitor for visible cracks

   With the ignitor removed, visually inspect the silicon nitride element for fractures, chips, or carbon tracking. Even a hairline crack can cause an open under thermal expansion.

4. Check ignitor wiring harness continuity

   Measure continuity on the harness from the IFC board connector to the ignitor connector. Repair or replace any harness segment with an open conductor.

5. Install replacement ignitor

   Handle the new silicon nitride element only by its ceramic base — never touch the element with bare skin. Torque the mounting screw to the specified value and reconnect the harness. Run a test heat cycle to confirm ignition.

When to call a professional

Ignitor replacement is a straightforward task for a qualified technician but requires care with silicon nitride elements and correct torque on the mounting hardware. If the ignitor resistance is within spec but E207 persists, the IFC board's ignitor monitoring circuit may be faulty — a licensed technician can differentiate a board input fault from an ignitor fault using control board diagnostic modes.