Error code reference

Lennox Furnace Error Code E 272

Soft lockout

Soft lockout - Exceeded maximum number of recycles, last recycle due to the pressure switch opening.

First step from the service manual

Check operation of low pressure switch to see if it is stuck closed on heat call. Check pressure of high 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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