Lennox Error Code E226 indicates High pressure switch failed closed. Start by checking the most common and safe items identified in the troubleshooting section. If the code returns after those checks, professional diagnosis is recommended.
Easy
High pressure switch failed closed
Unknown
High pressure switch remains closed when it should not
Check operation of high pressure switch closing on heat call; measure operating pressure; inspect vent and combustion air inducer for correct operation and restriction; resumes normal operation after fault cleared
High pressure switch, vent system, combustion air inducer
Call an HVAC technician if the error persists after completing the recommended basic troubleshooting steps or if the system repeatedly locks out.
Disconnect power before inspecting the equipment. Never bypass safety devices or operate the system if you suspect unsafe conditions.
Learn more about the furnace components and operating conditions commonly associated with diagnostic error codes: