Error code reference

Lennox Furnace Error Code E 274

Soft lockout

Soft lockout - Exceeded maximum number of recycles, last recycle failed due to the limit circuit opening or limit remained open longer than 3 minutes.

First step from the service manual

Shut down system. 1-hour soft lockout. Check firing rate and air flow. Check for blockage. Clears when heat call finishes successfully.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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