Furnace Flashing Red Light 5 Times: What Does It Mean?

What Does the Blinking Red Light On My Furnace Mean?
What Does the Blinking Red Light On My Furnace Mean? from www.docdancer.com


If you have a furnace at home, you may have encountered situations where the red light on your furnace starts flashing five times. This flashing red light is not something to be ignored, as it indicates a potential issue with your furnace. In this article, we will discuss what it means when your furnace’s red light flashes five times and what steps you can take to resolve the issue.

Understanding the Flashing Red Light

When the red light on your furnace flashes five times, it is usually a sign of a problem with the furnace’s ignition system. The ignition system is responsible for lighting the furnace’s burners, and if it fails to do so, the red light will start flashing to indicate an issue.

Possible Causes

There are several possible causes for the furnace’s red light to flash five times. One common cause is a dirty or faulty flame sensor. The flame sensor is a small device located near the burners that detects whether the burners are lit. If the sensor is dirty or malfunctioning, it may not detect the flame, causing the red light to flash.

Another possible cause is a blocked or restricted flue vent. The flue vent is responsible for removing the combustion gases from the furnace. If the vent is blocked or restricted, the furnace may not be able to properly ignite, resulting in the flashing red light.

Additionally, a malfunctioning ignitor or a faulty gas valve can also cause the red light to flash five times. These components are crucial for the ignition process, and if they are not functioning correctly, the furnace will not be able to ignite, leading to the flashing red light.

Troubleshooting Steps

If your furnace’s red light is flashing five times, there are a few troubleshooting steps you can take before calling a professional. Start by checking the flame sensor and cleaning it if necessary. Gently remove any dirt or debris from the sensor using a soft cloth or fine-grit sandpaper.

Next, inspect the flue vent for any blockages or restrictions. Clear away any debris or obstructions that may be preventing proper airflow. Ensure that the vent is not obstructed by snow, leaves, or other objects that may have accumulated around it.

If the above steps do not resolve the issue, it is best to call a professional HVAC technician. They will have the necessary tools and expertise to diagnose and fix the problem safely and effectively.


A furnace flashing a red light five times is a clear indication of an issue with the ignition system. Possible causes include a dirty flame sensor, blocked flue vent, malfunctioning ignitor, or faulty gas valve. While some troubleshooting steps can be taken, it is recommended to seek professional help if the issue persists. Regular furnace maintenance and inspections can help prevent such issues in the future, ensuring your furnace operates efficiently and safely.