TL;DR
A flame sensor is the thin metal rod positioned in a gas furnace's burner flame that proves ignition by conducting a tiny flame-rectification current — microamps — back to the control board; if the signal disappears, the board closes the gas valve within seconds. Oxide buildup on the rod is the most common furnace no-heat call: the unit lights, runs a few seconds, and shuts down, often three tries before lockout.
What it means
A flame sensor is the thin metal rod positioned in a gas furnace's burner flame that proves ignition by conducting a tiny flame-rectification current — microamps — back to the control board; if the signal disappears, the board closes the gas valve within seconds. Oxide buildup on the rod is the most common furnace no-heat call: the unit lights, runs a few seconds, and shuts down, often three tries before lockout. Cleaning the rod with fine abrasive restores the signal; actual sensor replacement is cheap and quick.
Where it sits in the glossary
Flame sensor is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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