Error code reference

Lennox Furnace Error Code E 271

Soft lockout

Soft lockout - Exceeded maximum number of retries, last retry failed due to the pressure switch opening.

First step from the service manual

Check pressure (inches w.c.) of low pressure switch closing on heat call. Measure operating pressure. Inspect vent and combustion air inducer for correct operation and restriction. 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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