MEDIUM URGENCY

Lennox 2 Flashes — Closed Pressure Switch With Inducer Off

2 flashes

Pressure switch stuck closed when inducer is off.

Brand: Lennox (Also covers Armstrong Air, Aire-Flo, Ducane) | Equipment: Gas Furnace

What This Code Means

2 flashes means the pressure switch shows closed contacts when the inducer motor isn't running. The switch should be open when there's no draft.

Most common

What: Switch contacts welded or stuck.

How to check: Test continuity at switch with inducer off.

Fix: Replace switch.

Shop parts

Less common

What: Board misreads switch state.

How to check: Test switch independently.

Fix: Replace board.

Shop parts

DIY fix for Lennox 2 flashes?

Pressure switch replacement is straightforward — usually 2 wires and 1-2 screws.

Cost?

Switch $25-60 plus optional labor.

Same on Armstrong/Ducane?

Yes.