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The genuine OEM Lennox 15K16 flame sensor safeguards your gas furnace by confirming the presence of a burner flame during every heating cycle. Through flame rectification, the sensor sends a small microamp current back to the control board, verifying combustion so the gas valve stays open only when it is safe. It is an essential part of your Lennox furnace's proof-of-flame safety system.
Common failure symptoms: A failing 15K16 sensor commonly causes the furnace to ignite and then flame out within seconds, repeated hard lockouts, intermittent or no heat, and short cycling. Oxidation or carbon buildup on the sensor rod is a frequent culprit, and a cracked or degraded sensor should be replaced rather than repeatedly cleaned.
Why OEM matters: Lennox control boards are tuned to a specific flame-sense signal threshold. Installing an OEM 15K16 ensures the correct rod material, length, and insulator so the board reads a clean, in-spec signal. This eliminates the nuisance faults and reliability problems that plague generic substitutes and restores dependable, code-compliant furnace operation.