Lennox Furnace Error Code E 226

E 226 means the high pressure switch has been detected in the closed position when it should be open. This switch monitors combustion airflow and must transition from open to closed during a heat call for the furnace to confirm safe operating conditions. Because the control board detected an unexpected closed state, the furnace shut down to prevent unsafe operation. The fault will clear and normal operation will resume once the underlying issue is corrected.

The furnace will not operate while E 226 is active because it has shut down as a safety precaution. You should not attempt to bypass or override the fault. The high pressure switch is part of the combustion safety circuit, and operating the furnace with a failed or stuck switch could mask a venting problem that poses a carbon monoxide risk.

Repair costs depend on the specific cause. If the issue is a blocked vent that can be cleared without parts, you may only pay a diagnostic or service call fee, typically in the range of $75 to $150. Replacing a faulty high pressure switch generally costs between $150 and $350 including parts and labor. If the combustion air inducer motor has failed, costs can range from $300 to $700 or more depending on the model and labor rates in your area.

Some basic checks are within reach of a knowledgeable homeowner, such as inspecting the vent terminations for visible blockages like ice or debris and checking the pressure tubing connected to the switch for water. However, testing the switch with a multimeter, measuring operating pressures, and inspecting the inducer motor require tools and experience that most homeowners do not have. A licensed HVAC technician should perform the full diagnosis to ensure the repair is done safely and correctly.

According to the fault code behavior, the furnace will resume normal operation after the fault condition is cleared. However, simply resetting the furnace without addressing the underlying cause will likely result in the error returning. The root cause, whether a faulty switch, blocked vent, or inducer problem, must be diagnosed and corrected before the system will operate reliably.