Lennox Furnace Error Code E224

E224 means the low pressure switch has been detected as stuck in the closed position during a heating call for longer than 150 seconds. The low pressure switch is a safety component that monitors draft pressure from the inducer motor. When it fails to open as expected, the furnace control board locks out the system and displays E224 to prevent unsafe operation. The fault points to either a failed switch, a venting restriction, or an inducer problem.

No, you should not attempt to bypass or override the E224 lockout. The low pressure switch is a safety device that confirms proper venting of combustion gases. A fault in this circuit could indicate that exhaust gases are not being safely removed from the home. Leave the furnace off and contact a qualified HVAC technician to diagnose and repair the fault before resuming normal operation.

Start by turning off the furnace and disconnecting power. Remove the pressure switch wiring and use a multimeter to check continuity across the switch terminals with no power applied and the inducer off. If the switch reads closed (continuity) in this state, it has failed and needs replacement. If the switch reads open, reconnect everything and measure the actual pressure at the switch port during inducer operation to compare against the switch rating, and inspect all vent piping for blockages or damage.

Resetting the furnace by cycling power may temporarily clear the E224 fault code, but the error will return if the underlying problem is not fixed. If the low pressure switch is physically stuck closed or the venting system is restricted, the same fault conditions will be present on the next heating call. A reset without a proper diagnosis and repair is not a lasting solution and could mask a safety issue.

Repair costs depend on the root cause. If only the low pressure switch needs replacement, parts and labor typically range from $100 to $300. If the issue involves the inducer motor assembly, costs can range from $300 to $700 or more depending on parts and labor rates in your area. A diagnostic service call to identify the cause is usually billed separately and commonly ranges from $75 to $150.