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ErrBase

Lennox Furnace Error Codes

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

5 error codes

CodeMeaning
270Lennox error code 270 means the furnace attempted ignition multiple times but failed to establish a confirmed flame and has locked out. The control board runs the full pre-ignition sequence but doesn't receive a valid flame signal from the sensor within the proving window. After enough failed attempts, the board locks and won't allow 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 doesn't respond correctly.
highintermediate
HUBThis hub covers alphanumeric codes on Lennox's digital control board display. The furnace uses a 2-3 character display that shows error codes continuously or in a rotating sequence when something's wrong. Older Lennox models without a display use LED blink codes, accessed by pressing the diagnostic button on the control board.
lowbeginner
RESET-PROCEDUREA Lennox furnace reset is a procedure used to clear the control board memory of temporary lockout codes or to restart the ignition sequence after a safety trip. It typically involves cycling power or interacting with the limit switches.
moderatebeginner