{"product_id":"oem-lennox-flame-sensor-18g89","title":"OEM Lennox Flame Sensor — 18G89","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e18G89\u003c\/strong\u003e flame sensor is a critical safety component in your gas furnace. It uses the principle of flame rectification to confirm that the burners have actually ignited, sending a microamp signal back to the control board. If no flame is detected, the board shuts off the gas valve to prevent a dangerous buildup of unburned fuel. This factory part is engineered to the exact resistance and positioning specifications of your Lennox furnace.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms:\u003c\/strong\u003e A failing or dirty \u003cstrong\u003e18G89\u003c\/strong\u003e flame sensor is one of the most frequent causes of furnace short-cycling. You may notice the burners light and then shut off after just a few seconds, repeated ignition attempts, or the furnace locking out completely and running only cold air. Oxidation and carbon buildup on the sensor rod weaken the flame signal over time.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e Aftermarket sensors often have slightly different rod length, alloy, or mounting geometry, which can produce a marginal flame signal that fails intermittently — especially frustrating on cold nights. The OEM Lennox \u003cstrong\u003e18G89\u003c\/strong\u003e guarantees the correct signal strength and a precise fit for reliable, safe operation season after season.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081114173811,"sku":"LNX-18G89","price":19.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-flame-sensor-straight-LNX-18G89.jpg?v=1783761013","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-flame-sensor-18g89","provider":"National HVAC Parts","version":"1.0","type":"link"}