Lennox Error Code E275 indicates Soft lockout – flame sensed out of sequence; flame signal is gone. 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
Soft lockout – flame sensed out of sequence; flame signal is gone
Unknown
Flame signal lost out of sequence, possible gas valve leak
Shut off gas; check for gas valve leak; 1‑hour soft lockout; clears when flame has been proven stable
Gas valve
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: