Lennox E226

What does Lennox E226 mean?

E226 means the high-pressure switch is stuck in the closed position when it should be open. The IFC checks that the high-pressure switch is open before initiating the inducer on second-stage demand; a switch that does not open indicates a stuck contact or residual pressure in the switch hose. The board logs E226 and aborts the second-stage sequence. The fault clears once the switch opens correctly.

Symptoms

• High-pressure switch reads closed with an ohmmeter when the inducer is off.
• E226 alert displayed on thermostat or control board at the start of a second-stage heating cycle.
• Furnace may fall back to first-stage operation or shut down entirely.
• Alert clears after a power cycle but returns on the next second-stage demand.

Common causes

• Trapped condensate in the high-pressure switch hose maintaining pressure on the diaphragm after inducer shutdown.
• Mechanical failure of the high-pressure switch with a stuck closed contact.
• Partially blocked inducer housing pressure tap maintaining residual pressure against the switch diaphragm.

Diagnostic steps

1. 01

   Verify switch state with inducer off

   Power down the furnace. Disconnect the high-pressure switch leads and measure continuity with the inducer stopped. A healthy switch should be open (no continuity) when no pressure is applied.

2. 02

   Drain and clear the high-pressure switch hose

   Remove the hose from the switch port and drain any trapped condensate. Blow through the hose to confirm it is clear. Reinstall and re-test switch continuity.

3. 03

   Clear the inducer housing high-pressure tap

   Remove the hose at the inducer housing high-pressure port. Clear any condensate or debris from the tap with a small wire or short burst of compressed air.

4. 04

   Replace high-pressure switch if contact remains closed

   If the switch reads closed with no pressure applied after clearing the hose and tap, the switch is mechanically failed. Install the Lennox OEM replacement high-pressure switch.

5. 05

   Run the furnace through second-stage heat cycles

   After repair, verify three consecutive second-stage heat cycles complete without E226 returning. Confirm the high-pressure switch opens properly after each inducer shutdown.

When to call a professional

Persistent E226 after switch replacement suggests an underlying draft or condensate management issue. A licensed technician can measure static pressure at the high-pressure tap, evaluate whether the inducer coasts down correctly, and assess condensate trap design to prevent water from accumulating in switch hoses.