Lennox Furnace Code E225: What It Means & How to Fix It
Compiled & reviewed by the HVAC Flash Codes editorial team · Updated 2026-06-25 · confidence: high
⚠️ Try the safe checks, then a pro
What does Lennox furnace code e225 mean?
High-pressure switch failed to close (open) — the high-stage pressure switch did not close when expected during a heat call. A 'Service Soon' condition that auto-clears once corrected. Most often caused by Restricted intake/exhaust vent or insufficient inducer vacuum.
E225
What your control shows. Your Lennox furnace displays Code E225 on its diagnostic readout.
What Lennox furnace code e225 means
High-pressure switch failed to close (open) — the high-stage pressure switch did not close when expected during a heat call. A 'Service Soon' condition that auto-clears once corrected.
Common causes
Restricted intake/exhaust vent or insufficient inducer vacuum
Blocked cold-end heater box, condensate drain, or drain strainers
Cracked or disconnected pressure-switch hose
Unit not level, or a faulty high-pressure switch
Homeowner-safe steps to try
Set the thermostat to OFF
Clear the outside intake/exhaust terminations of any blockage
Confirm the condensate drain is clear and draining
Replace the air filter and cycle power to retry
When to call a licensed HVAC technician
If the basic checks below don't clear the code, the fault recurs, or anything involves the gas valve, burners, flame sensor or wiring, stop and book a licensed HVAC technician. Repairs to the combustion or gas system are not DIY.
⚠️ Safety first. Gas furnaces burn fuel and produce combustion gases. If you ever smell gas (a rotten-egg or sulfur odor), hear hissing, or your carbon-monoxide alarm sounds, do not touch light switches, thermostats, or the furnace — leave the home immediately and call your gas utility's emergency line or 911 from outside. Homeowners should limit themselves to simple, safe steps: setting the thermostat, checking and replacing the air filter, confirming the furnace switch and breaker are on, keeping supply registers and return grilles open, and clearing snow, ice, or debris from outdoor vent and intake terminations. Never bypass, jumper, or reset safety switches (limit, flame-rollout, or pressure switches), never open the gas valve or burner compartment, and never attempt combustion, electrical, or control-board repairs yourself. Error codes point toward a problem but are not a substitute for proper diagnosis — when in doubt, turn the system off and call a licensed HVAC technician. Keep working carbon-monoxide detectors on every level of your home.
When to call a pro: Call a licensed technician if the code persists — measuring operating vacuum, inspecting hoses, and testing the pressure switch require a professional. Do not jumper the switch. If you smell gas, leave and call the gas utility from outside.
Lennox furnace code e225 FAQ
What does Lennox furnace code e225 mean?
High-pressure switch failed to close (open) — the high-stage pressure switch did not close when expected during a heat call. A 'Service Soon' condition that auto-clears once corrected.
What causes Lennox furnace code e225?
Common causes: Restricted intake/exhaust vent or insufficient inducer vacuum; Blocked cold-end heater box, condensate drain, or drain strainers; Cracked or disconnected pressure-switch hose; Unit not level, or a faulty high-pressure switch.
Can I fix Lennox furnace code e225 myself?
You can safely try: Set the thermostat to OFF; Clear the outside intake/exhaust terminations of any blockage; Confirm the condensate drain is clear and draining; Replace the air filter and cycle power to retry. Call a licensed technician if the code persists — measuring operating vacuum, inspecting hoses, and testing the pressure switch require a professional. Do not jumper the switch. If you smell gas, leave and call the gas utility from outside.
Sources: lennox.com · lennox.com. General information for homeowners, not professional advice — confirm against your furnace's manual and a licensed technician.