Lennox EL296UHV Error Code E 226: High Pressure Switch Failed Closed
What Does Code E 226 Mean?
Error code E226 on the Lennox EL296UHV means the high pressure switch failed closed. On this two-stage furnace the high pressure switch should be OPEN at rest and only close once the combustion-air inducer reaches the high-fire speed that produces strong draft. With E226 the switch is closed when the control expects it open, so the board cannot trust it to reflect real draft conditions and flags the fault.
A high pressure switch that stays closed regardless of inducer state can no longer act as a reliable safety device — it would let the control believe high-fire venting is proven even when it is not. Rather than rely on a switch it cannot trust, the control reports E226. This is the mirror image of E225, where the same high pressure switch fails to CLOSE when it should, and it parallels E224 on the low-fire side.
The most likely cause is a mechanically stuck diaphragm or contacts that have welded or corroded closed. Condensate moisture in the switch housing or hose can also hold the contacts closed. E226 is rated lower severity than E225 because the fault is generally the switch itself rather than a blocked flue, but it still requires a technician because a stuck-closed high switch defeats a high-fire safety interlock.
What You'll Notice
- The furnace will not run a normal cycle and the display shows E226
- The seven-segment display shows E226 after a call for heat
- Heating is inconsistent, sometimes running and sometimes faulting
- The code returns even though the outdoor vent terminations are clear
- The furnace may hesitate at the point where it would normally step up to high fire
How This Is Diagnosed
A technician checks the high pressure switch's state with the inducer off or at low speed, expecting it to read open. Contacts that are closed when no high-fire draft exists indicate a stuck switch. They inspect the high-switch hose for trapped condensate or a pinch that could hold pressure on the diaphragm, and check the wiring for a short across the terminals that would mimic a closed switch.
With a manometer they verify the actual draft (in inches of water column) across the low- and high-fire inducer speeds, confirming the switch opens and closes at its rated thresholds rather than staying latched. Because the switch is a sealed safety device, replacement and any tubing correction are technician tasks, not homeowner repairs.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The display shows E226 and the furnace will not complete a normal cycle
- Heating is inconsistent and the code comes and goes
- The outdoor vent terminations are clear but the high switch still reads closed at rest
- The high-switch hose shows condensate, kinks, or a loose connection
- The furnace hesitates when it would normally step up to high fire
Frequently Asked Questions
How is E226 different from E225?
They are opposite failures of the same high pressure switch. E225 means the switch would not close when the inducer reached high-fire speed; E226 means the switch is stuck closed when it should be open. Both leave the switch unable to prove high-fire draft honestly.
Why does the EL296UHV have both a high and a low pressure switch?
It is a two-stage furnace whose inducer changes speed between firing rates. The low switch proves draft on low fire and the high switch proves draft on high fire, so each firing rate has its own venting safety check.
Can I just reset the furnace to clear E226?
A stuck switch keeps re-tripping the fault until the switch or its tubing is corrected. The control resumes normal operation only after the underlying condition is resolved, which a technician should handle.
✓ Verified against manufacturer service manual — March 2026