Lennox E223 Error Code

What does Lennox E223 mean?

E223 means the low-pressure switch did not close during a heating call. The SL280DFNV uses a low-pressure switch to confirm the combustion air inducer is producing adequate draft before allowing ignition. When the switch stays open — meaning draft pressure never reached the switch setpoint — the board logs E223 and prevents ignition. The fault clears when the switch successfully closes on a subsequent call.

Symptoms

• Furnace inducer runs but burners do not light — heat call aborts after the inducer purge period.
• E223 alert displayed on the thermostat or control board.
• Condensate trap or drain line may be visibly backed up with water.
• Alert occurs consistently or intermittently depending on vent or drain restriction severity.

Common causes

• Blocked or restricted PVC vent pipe reducing draft below the low-pressure switch setpoint.
• Clogged condensate trap or drain preventing proper pressure switch operation.
• Disconnected or kinked pressure switch hose between the inducer housing and the switch.
• Failed combustion air inducer motor not producing adequate draft pressure.
• Faulty low-pressure switch that will not close at the correct draft pressure.

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Diagnostic steps

1. Inspect vent pipes for blockage

   Check both intake and exhaust PVC pipes for debris, ice, bird nests, or collapsed sections. Clear any obstruction and verify proper pipe pitch and termination clearance per the SL280DFNV IOM.

2. Clear the condensate trap and drain

   Remove and flush the condensate trap with water to clear any algae, scale, or debris. Verify the drain line flows freely. A backed-up trap can reduce draft and cause the low-pressure switch not to close.

3. Inspect pressure switch hoses

   Check all hoses connected to the low-pressure switch for cracks, kinks, or disconnected ends. Reconnect any loose hose and replace cracked tubing.

4. Measure inducer draft pressure

   Connect a manometer to the pressure tap on the inducer housing. With the inducer running, compare measured draft (in. w.c.) against the low-pressure switch closing setpoint in the IOM. Low draft indicates a weak inducer motor or restricted vent.

5. Test or replace the low-pressure switch

   Apply the specified closing pressure manually to the switch with a manometer and verify switch continuity. Replace the switch if it does not close at the rated setpoint.

When to call a professional

A draft pressure reading below spec with an unobstructed vent indicates a failing inducer motor or capacitor. Inducer replacement on the SL280DFNV requires verifying motor speed and confirming pressure switch calibration — a licensed technician has the pressure measurement tools and motor diagnostic capability to make this determination accurately.