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How Do You Get Your Furnace Out Of Lockout Mode?

Modern furnaces are outfitted with a variety of safety features. As a result, your gas furnace is equipped with several sensors to keep the unit running smoothly. When one of these sensors detects an anomaly or an unsafe condition inside the gas furnace, the furnace controllers immediately force a shutdown to prevent damage and ensure safety. The gas furnace enters an ignition lockout after several resets.

Causes Of Furnace Lockout

Here are a few potential reasons for furnace lockout:

  • Defective Flame Sensors: A faulty flame sensor is a leading suspect when it comes to a furnace ignition lockout. When the furnace is turned on, the sensor checks to see if there is a fire. As a result, if the sensor fails, it will not detect the flame. As a result, the controller will activate, preventing the gas furnace from completing the ignition process. Modern furnaces enable the ignition process to fail no more than twice before locking out the system.

  • Faulty Ignitor: Another frequently encountered lockout culprit is the igniter. If your furnace igniter does not ignite within a few seconds, the flame sensor will not detect the flame, and the controller will prevent the furnace from starting. After the third attempt, your furnace will most likely lockout. The pilot light on your gas furnace could cause the lockout.

  • Limit Switch Response: An ignition lockout can also be caused by dirty air filters connected to your gas furnace. Because of the poor airflow and circulation, a limit switch that screens fuel and air pressure is tripped. Although it is more difficult to detect, modern HVAC systems include status lights indicating which sensor falters during a failed ignition.

Quick Fixes For The Ignition Lockout

Even though lockout mode faults and resets differ from manufacturer to manufacturer, most employ a straightforward reset process that entails cutting the furnace’s power for at least thirty seconds and then turning it back on. The interrupted power supply removes the lockout, which enables the device to try normal operation once more.

Hire an HVAC professional to assist you with your gas furnace ignition lockout problem. Some quick fixes that you can do on your own are:

  • Clean the air filters. A clogged filter could prevent enough airflow from passing through. This restricted airflow could lead to serious issues such as limited switch failings and lockouts. As a result, it is recommended that you inspect air filters for cracks and malfunctions and replace them as needed.
  • Clean or completely replace the flame sensor. This necessitates a thorough examination of cracks and indications of damage.
  • Clean out your vents and pipes. Pipe clogs and other obstructions will cause more problems.


A reset is required regardless of how you got into a furnace ignition lockout. The best way to reset your furnace is to turn it off and back on after about 30 minutes. If that fails, contact our HVAC service experts and follow their directions. If you’re facing a furnace lockout and want a heating replacement in Kenner, LA, get in touch with Climate Tamers.

Our technicians will perform a few mandatory tests to ensure safety before unlocking your furnace. If you are looking for a heating installation professional in Kenner, LA, you can contact us at (504) 919-0822.