The Lennox furnace E228 error code indicates that the pressure switch is open when it should be closed during the ignition sequence. This means the furnace’s internal computer is sensing a lack of proper airflow or dangerous exhaust draft conditions, and it shuts down the heating cycle to prevent carbon monoxide from backing up into your home. Fortunately, clearing the Lennox furnace E228 error is often a matter of clearing a blocked pipe or a clogged drain tube rather than buying expensive new mechanical parts.
⚠️ SAFETY FIRST: You will be diagnosing a gas appliance that deals with carbon monoxide and 120 volts of electricity. Always turn off the furnace’s dedicated circuit breaker and shut off the main gas valve leading to the unit before removing the front metal doors to inspect the internal components.
What Causes the Lennox Furnace E228 Error Code?
When your thermostat calls for heat and the display flashes the Lennox furnace E228 error, the draft inducer motor turns on, but the pressure switch fails to detect the vacuum it creates. The most common triggers for this critical safety lockout include:
- Blocked exhaust flue or intake pipe: A bird’s nest, dead leaves, a buildup of ice, or heavy snow has physically blocked the PVC exhaust pipes outside your house, restricting airflow.
- Clogged condensate drain: In high-efficiency furnaces, water vapor condenses into liquid. If the internal drain trap or the vinyl drain hose gets clogged with gunk, water backs up into the inducer housing, tripping the pressure switch.
- Cracked or loose pressure switch hose: A tiny rubber tube connects the draft inducer to the pressure switch. If this tube has a hairline crack, is dry-rotted, or falls off, the vacuum is lost.
- Clogged inducer port: The small metal nipple on the inducer motor where the rubber hose attaches can get clogged with hard water scale or rust.
- Faulty pressure switch: The physical diaphragm inside the plastic pressure switch has stiffened with age or the internal electrical contacts have failed.
Tools You Will Need for This Repair
To properly diagnose, clean, and resolve the Lennox furnace E228 error, gather these basic tools:
- A digital multimeter (crucial for testing the switch for continuity).
- A small paperclip or a piece of stiff wire (to clean out the inducer port).
- A Shop-Vac (to clear out clogged drain lines or exhaust pipes).
- A flashlight.
How to Fix Lennox Furnace E228 Error Step-by-Step
You can often restore your home’s heat and clear the Lennox furnace E228 error in under an hour by following these DIY troubleshooting steps:
- Check the Exterior Pipes: Go outside your house and locate the white PVC exhaust and intake pipes. Ensure they are completely clear of snow, ice, leaves, and debris. Use a flashlight to look deep inside.
- Inspect the Rubber Hose: Turn off the power and remove the top front panel of your Lennox furnace. Locate the round, pancake-shaped plastic pressure switch. Check the small rubber hose connecting it to the metal inducer motor. If the hose has cracks, replace it with a standard vacuum hose from an auto parts store. Ensure it is attached tightly at both ends.
- Clear the Inducer Port: Pull the rubber hose off the inducer motor side. Take your small paperclip and carefully poke it into the metal nipple on the inducer housing to clear out any hard rust or scale buildup blocking the air path.
- Clear the Condensate Trap: Follow the vinyl drain tubes to the small plastic condensate trap box. If it is full of dark sludge, remove it, wash it out thoroughly in a sink, and reinstall it. A clogged trap is a primary cause of the Lennox furnace E228 error in high-efficiency models.
- Test the Pressure Switch: If everything is clear, pull the two wires off the pressure switch. Turn the furnace power on and let the inducer motor start spinning. Set your multimeter to Ohms (Ω). Touch the probes to the switch terminals. If it reads infinite resistance (OL) while the motor is running at full speed, the switch is permanently stuck open and must be replaced.
How to Reset a Lennox Furnace (Hard Reset)
After clearing a blockage or installing a new switch, you must clear the Lennox furnace E228 error from the memory. Turn the furnace power off at the circuit breaker or the wall switch for 5 full minutes. Turn it back on and set your thermostat to call for heat. Watch the sequence to ensure the inducer motor starts, the ignitor glows, and the gas valve clicks open safely.
When to call a professional?
If you have verified the exterior pipes are clear, the hoses are perfect, and the drain is spotless, but the Lennox furnace E228 error persists, you may be dealing with a failing draft inducer motor that isn’t pulling enough vacuum, or worse, a cracked heat exchanger. Because diagnosing combustion issues and handling gas valves requires specialized manometers and carbon monoxide detectors, it is strongly recommended to contact a certified local HVAC technician to complete the repair safely.