Lennox Furnace Error Code E 271

E 271 is a soft lockout code indicating the furnace exceeded its maximum number of ignition retries, with the last attempt failing because the pressure switch opened during the heating sequence. The pressure switch monitors draft created by the inducer motor, and if it loses that signal, the control board terminates the ignition attempt. This code points to a problem in the venting system, the inducer motor, or the pressure switch circuit itself. The furnace will attempt to recover automatically once the heat call ends.

Start by inspecting the flue vent system from the furnace to the exterior termination cap for any blockages, disconnections, or ice accumulation. Next, check the pressure switch hoses for cracks or loose connections, and inspect the condensate drain for clogs. If the venting appears clear, use a manometer to measure the actual pressure at the low pressure switch during a heat call and compare it to the switch closing specification. If the inducer motor is suspect, check for free rotation, unusual noise, and proper electrical supply to the motor.

Repair cost depends entirely on the root cause. Clearing a blocked vent or reconnecting a pressure switch hose may involve only a service call fee, typically in the range of $75 to $150. Replacing a faulty pressure switch generally costs between $100 and $250 including parts and labor. An inducer motor replacement is more involved and can range from $300 to $700 or more depending on the specific model and labor rates in your area.

Because E 271 is classified as a soft lockout, it is designed to clear on its own once a heat call completes successfully, without requiring a manual power reset. However, if the underlying cause such as a blocked vent or weak inducer is not corrected, the code will return on the next heating cycle. Performing a manual reset without diagnosing the root cause only delays the fault and can lead to repeated lockout events.

The E 271 soft lockout is a protective response, meaning the furnace has already stopped the ignition attempt to prevent unsafe operation. Running the furnace with an unresolved pressure switch or venting issue is not recommended, as incomplete combustion or improper venting of combustion gases can pose a carbon monoxide risk. The system should be inspected and the root cause corrected before relying on the furnace for continued heating.