OEM Lennox Pressure Switch — 57M67

The genuine OEM Lennox 57M67 pressure switch is a critical safety control that monitors venting airflow in your Lennox furnace. It confirms that the draft inducer is drawing combustion gases properly before the control board allows the gas valve to open and the burners to ignite. This ensures your furnace only fires when it can safely exhaust flue gases, protecting your home from carbon monoxide risk.

Common failure symptoms include a furnace that ignites and then shuts off, repeated short cycling, a blower that runs without heat, or a control board flashing a pressure switch fault code. Blocked vent pipes, a cracked hose, or a fatigued diaphragm inside the switch are frequent culprits. When the 57M67 can no longer close reliably on the correct pressure setpoint, the furnace locks out to stay safe.

Choosing an OEM Lennox part matters because pressure switches are calibrated to a specific trip point measured in inches of water column. A generic switch with the wrong setpoint can allow unsafe operation or cause nuisance lockouts. The 57M67 is factory-matched to Lennox specifications for a direct, reliable fit and correct performance in the systems it was engineered for.