OEM Lennox Pressure Switch — 40W06

The genuine OEM Lennox 40W06 pressure switch safeguards your Lennox furnace by confirming adequate combustion airflow and venting before ignition is permitted. It monitors the negative pressure produced by the draft inducer, ensuring exhaust gases are being properly evacuated so the burners can fire safely.

A failing 40W06 switch, or a switch with a blocked or cracked sensing hose, commonly causes the furnace to fail to ignite, cycle the inducer on and off without lighting, or display a pressure-switch error at the control board. These lockouts are the system's way of preventing unsafe combustion when proper draft can't be verified.

OEM replacement is important because this switch is factory-calibrated to a specific pressure threshold matched to your Lennox unit's venting configuration. An incorrect aftermarket switch can trip too early, too late, or not at all, risking either nuisance shutdowns or unsafe operation. The authentic 40W06 restores dependable, code-compliant ignition and protects both your equipment and your household.