Lennox Error Code E273 indicates Soft lockout – exceeded maximum number of recycles; last recycle due to flame failure. 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 – exceeded maximum number of recycles; last recycle due to flame failure
Unknown
Flame sensor signal lost during recycles
Check micro‑amperes of flame sensor using diagnostics; clean or replace sensor; measure neutral‑to‑ground voltage to ensure good ground; clears when heat call finishes successfully
Flame sensor, grounding
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: