Trane Furnace Red Light Flashing [Solved]

The Trane furnace red light flashing indicates functionality and errors of the furnace. Whether the furnace is responding properly or having a problem is indicated by the speed and number of flashes of the red light. 

trane furnace red light flashing

While a slow blink of the red light refers to normal operations, flashing the red light rapidly or in a sequence can refer to internal furnace issues.

In this guide, we will discuss the Trane furnace red light flashing issue and what we understand about it. So, continue reading till the end of the guide. 

Table Of Contents

Trane Furnace Red Light Flashing [Solved]

The Trane furnace red flashing light helps users to understand the working condition of the furnace and what problem it’s facing.

Here, we will take a look at each and every Trane furnace red light blinking sequence and the reasons behind it. 

1. Flashing 2 Times

The Trane furnace red light flashing 2 times signals that the furnace has gone into a hard lockout. This typically happens when the flame sensor can’t detect a flame within a certain period of time after turning the furnace on. 

The hard lockout can often be resolved by resetting the furnace. However, if the resetting doesn’t fix the lockout, then be sure the followings are the culprits:

  • A faulty ignitor
  • Loose wiring
  • Blocked airflow
  • Malfunctioning flame sensor
  • Cracked heat exchanger 
  • And a faulty control board


  • Repair or replace the ignitor, control board, flame sensor, and heat exchanger. 
  • Check the wiring and make sure that all the wires are properly connected. 
  • Clean all the pipes properly and maintain a proper cleaning schedule. 

2. Flashing 3 Times

When the Trane furnace is switched on, the pressure switch senses the pressure in the furnace and closes the sensor to let the power pass to the ignitor.

The furnace shuts down its operations when the pressure switch detects a negative pressure and this is indicated by the Trane furnace red light flashing 3 times. 

This Trane furnace red light blinking sequence ensures that the system is experiencing a pressure switch error. The most common reasons behind it are: 

  • Faulty Pressure Switch 
  • Improper Wiring, 
  • Damaged Hose, 
  • Exhaust Vent Blockage, 
  • And A Damaged Sensor. 


  • Replace or repair the pressure switch, hose, and sensor. 
  • Correct the wiring and ensure they are perfectly secure in place. 
  • Remove all the objects blocking the exhaust vent and clean the air vents properly. 

3. Flashing 4 Times

If you see your Trane furnace red light blinking 4 times, then it is a clear indication that there is an issue with the open temperature limit circuit.

The purpose of the temperature limit switch is to control the operations of the blower fan in the furnace and detect the air temperature to prevent overheating. 

When the temperature within the furnace reaches a higher temperature than normal, the limit switch trips to protect the furnace components.

This opens the temperature limit circuit and causes the red light to flash 4 times. The most common reasons why this occurs are: 

  • Dirty Air Filter, 
  • Faulty Limit Switch, 
  • And Overheating Within The Furnace. 


  • Clean the air filter properly on a regular basis. 
  • Replace the limit switch with a new one. 
  • Turn the furnace off and wait for the temperature to drop. Check the thermostat settings and ensure that it’s set properly. 

4. Flashing 5 Times

The Trane furnace red light flashes 5 times when the system detects a flame when there is no flame in the burner.

This causes the furnace to shut down its operations in order to ensure safety. The most common reasons why users encounter this issue are:  

  • The flame sensor is dirty or faulty 
  • Gas valve problems
  • And a lingering flame in the burner is present 


  • Clean the flame sensor properly or replace it. 
  • Check the gas valve and replace it with a new one. 
  • Take out the burner tray and clean all the accumulation of dirt, debris, etc. 

5. Flashing 6 Times

When the control board of the furnace detects poor grounding or reversed polarity in the furnace, it results in the Trane furnace red light flashing 6 times.

The furnace won’t be able to continue its usual operations unless the issues are resolved. The problem typically occurs due to: 

  • Skinned wires
  • Ignitor grounding
  • Faulty control board
  • Extremely low voltage
  • Poor furnace grounding
  • And reversed AC power


  • Replace the wires and ensure proper connection. 
  • Resolve the grounding issues along with AC power and low voltage. 
  • Check and replace the control board. 

6. Flashing 7 Times

The Trane furnace red light blinking 7 times indicates that the furnace is encountering an issue with the gas valve circuit. If there is a problem with the gas valve circuit, it will not be able to supply the required gas to the furnace. 

This will prevent the flame from burning properly; thus, causing the system to shut down its operations. The gas valve circuit error occurs due to: 

  • The gas valve being closed or faulty
  • Clogged gas pipes
  • And loose wiring 


  • Examine the gas valve and ensure that it’s turned on. Replace the gas valve if necessary. 
  • Clean the gas pipes and maintain a proper cleaning schedule. 
  • Examine the wiring and secure the connection properly in place. 

7. Flashing 8 Times

When the Trane furnace is turned on, the flame sensor detects a flame to ensure that the furnace is working and heating up properly.

When the flame sensor detects a poor flame signal, it flashes the red light 8 times. The reasons behind the Trane furnace red light flashing 8 times are:

  • Dirty or faulty flame sensor
  • Low gas pressure
  • Loose wiring
  • And a faulty control board


  • Replace and repair the faulty flame sensor and control board. 
  • Check the gas pressure and set it correctly. 
  • Put the wiring properly in place to ensure a stable connection. 

8. Flashing 9 Times

In case your Trane furnace red light flashes 9 times, it is a signal to check the ignitor of the furnace.

When the furnace is on, the ignitor heats up and warms the burner tray which in turn increases the temperature of the room. The problem typically arises because of: 

  • The Ignitor Is Faulty Or Dirty 
  • Improper Wiring, 
  • Faulty Connection, 
  • And A Damaged Control Board. 


9. Solid Red Light

If you notice the Trane furnace’s red light constantly flashing, then this means that the furnace is in perfect working condition.

There are no internal or external issues affecting the performance and the furnace is heating up the room properly. 

How To Reset Trane Furnace

The majority of the problems causing the Trane furnace red light to flash can be resolved by resetting the furnace. The steps for resetting the furnace are: 

  • Unplug the Trane furnace from the power outlet. 
  • Locate the reset button and switch on the furnace. 
  • Press the reset button once and wait for the operations to stop. 
  • Press the reset switch for 30 seconds and plug the Trane furnace back in. 
  • Turn the furnace on and ensure that it’s working properly. 

On top of that, make sure that you properly maintain the furnace and keep it clean on a regular basis in order to ensure a proper heating experience. 

How To Maintain A Trane Furnace Properly

Maintaining a Trane furnace is quite easy and doesn’t require much time or money. In order to ensure the proper functioning of the furnace, clean the pipes, switches, and other components properly on a regular basis.

This will prevent the components and pipes from clogging and will perform perfectly. 

Ensure that all the parts and components of the Trane furnace are in perfect working condition. Examine the components on a regular basis and make the necessary repairs or replacements.

This will help you to protect your Trane furnace from major damage or problems. Make sure to keep an eye on the temperature and gas settings to ensure that they are in the right setting. 


How Do You Read A Trane Furnace Error Code?

Keep an eye on the red light of the Trane furnace to understand the error code. The blinking sequence of the red light will indicate the problem. 

How Long Does It Take Trane Furnace To Reset?

The Trane furnace takes a minute or two for resetting. Press the reset button for 30 seconds after unplugging the furnace and plug it back in. 


Now you know the sequence and reasons behind the Trane furnace red light flashing with their solutions. So, whenever you encounter a red light blinking, take help from our guide to identify the problem and solve it. 

If you have any questions about the Trane furnace, don’t hesitate to leave a comment below. We will get back to you with the best possible answer to your question. 

About David

I am David who loves doing research and finding out the best solution to any type of heating appliance issues like heaters and fireplaces. Whenever I find the perfect solutions to any issues of heating appliances after doing in-depth research, I love to share them with my readers. Thus, my aim is to minimize my readers' struggles and solve their troubles with their heating appliances. More about us .

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