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Lennox Furnace Error Codes

All Lennox furnace error codes with step-by-step troubleshooting, multimeter specs, and OEM part numbers.

4 error codes

CodeMeaning
270Lennox furnace error code 270 means the furnace attempted ignition multiple times but failed to establish a confirmed flame and has locked out. The control board goes through the full pre-ignition sequence (inducer preheat, ignitor heat-up, gas valve open) but does not receive a valid flame signal from the flame sensor within the proving window. After a set number of failed attempts, code 270 locks the board and prevents further starts until reset.
highintermediate
E223The primary pressure switch in the induced draft circuit did not close during startup. On SL280V and EL296V models, the cylindrical condensate trap uses an internal check valve that deteriorates with age, allowing air to bypass the sensing circuit and producing E223 even when the drain line itself is physically clear. E223 blocks gas valve operation to prevent unventilated ignition.
highintermediate
E228Lennox furnace error code E228 means the induced draft blower motor (inducer) has stalled, failed to start, or is running outside its expected speed parameters. The inducer motor is the fan that creates negative draft pressure in the heat exchanger and vents combustion gases. On Lennox variable-speed models like the SL280V and EL296V, the control board monitors inducer speed electronically and trips E228 when the motor does not respond correctly.
highintermediate
HUBThis hub covers Lennox furnace alphanumeric error codes displayed on the digital control board panel. Lennox furnaces use a two or three character display that shows error codes either continuously or in a rotating sequence when a fault is active. Some older Lennox models without a display use LED blink codes read by pressing the diagnostic button on the control board to scroll through the fault history.
lowbeginner