Trane Error Code 126 – Troubleshooging Guide

Flashing lights and error codes are the HVAC equipment’s way of communicating with us. 

A Trane error code 126 indicates that there is a communication malfunction between your HVAC unit and the thermostat; in a Trane 950, the code would mean a low-temperature lockout. In any case, the best way to deal with the issue is to reset the whole system.

Trane Error Codes

Here are the main error codes that you might come across if you have a Trane furnace. 

Error CodeMeaningPotential Issue
The red light always onThere is a control failureA problem with the control panel
The red light always offThe power is offCheck the power supply
2 blinksThere is a flame failureCheck: Gas supplyFlame rodWiring
3 blinksA problem with the pressure switchCheck for blockage in the condensate drain and in the vent
4 blinksThere is an issue with the temperature switchCheck for: Ductwork issueBlocked filterBlocked heat exchanger
5 blinksA flame has been sensed when a flame should not be presentThe possible issues include:A stuck or leaky gas valveA faulty flame sensor
6 blinksPoor grounding or a reversed polarity issueCheck line voltage polarity and the wiring
7 blinksThere is something wrong with the gas valve circuitTest the gas valve
8 blinksThe flame is too lowPossible issues:Insufficient gas pressureA faulty flame sensor
9 blinksAn issue with the igniterCheck and test the flame igniter

Read: Trane Furnace Error Codes -Troubleshooting Guide

Trane Error Code List

Below you will find the error codes for your Trane split system.

Error CodePotential Issue
E1High-pressure protection
E2Anti-freezing protection
E4Air exhaust high-pressure protection
E5Air conditioner overload protection
E6Communication failure between outdoor and indoor unit
E8High-temperature protection
H6An issue with the indoor motor
C5Jump wire malfunction
F1Short circuit, check the indoor ambient sensor
F2Short circuit, check the indoor evaporator sensor
F3Short circuit, check the outdoor ambient sensor
F4Short circuit, check the outdoor condenser sensor
F5Short circuit, check outdoor air exhaust sensor
F6There is a system overload
F8Overcurrent issue
F9An issue with the air exhaust
PHCheck the voltage of the DC generatrix
U3Check DC bus voltage
PLLow DC bus voltage
EUOver-temperature
U7An issue with the four-way valve
U9Zero-crossing detected in the outdoor unit
FHAnti-freezing limit

Trane 1050 Error Codes

Code 67.06 indicates that there is an issue with the suction temperature sensor in cooling mode. There might be an open circuit or it could have shorted.

Suction temperature is the temperature of the evaporator outlet. If you ever see this code, you would have to check the sensor and replace it, in case the element is damaged.

Read: Cost Of The Heat Pump: Everything You Need To Know About It

Trane Comfortlink II Error Codes

Trane’s Comfortlink II technology is, basically, a zoning system that lets you send cooled or heated air to particular areas of your house.

Code 79 indicates that the low-pressure switch is open. This can be caused by a clogged air filter, a frozen evaporator coil, or a low level of refrigerant.

The code will also show if the actual switch is faulty.

You can try resetting the system to see if it helps and you might have to check the elements mentioned above to find the root cause of the problem. 

Read: How To Choose Furnace Filter?

Trane Error Code 126

If the thermostat had broken the electrical circuit (this might happen when the outdoor temperature gets too low), your Trane thermostat will show the 126 error code.

The code can also indicate poor communication between the thermostat and your HVAC unit.

You can try resetting the system – turn the units off, wait for about and minute, and then turn everything back on. If the error code did not go away, then you might want to contact an HVAC expert.

Trane Error Code 53

If you have a Honeywell thermostat wired to your Trane unit, then error code 53 means that the outdoor sensor is failing.

The same code on a Trane Comfortlink II heat pump also indicates that the contact with the outdoor air sensor has been lost.

Resetting the system is going to help in the majority of cases.

Trane Error Code 67

Error codes 67.04 and 67.06 might mean that there is a problem with the suction temperature sensor (dome sensor). This element is located in the condenser and the error code might show up, if the actual sensor, the communication, or the connections are damaged.

A professional would have to perform a lock-out procedure to isolate power for safety and partially disassemble the unit. This will help figure out what the root cause of the problem is.

Trane Error Code 89

Code 89 means ‘equipment is missing’. It looks like the equipment that has been automatically discovered during set-up is no longer communicating with the system.

Here are a few possible causes of such an issue:

  • The outdoor unit breaker had tripped
  • The OD transformer or fuse is open
  • The field control wiring to the outdoor unit is open
  • The connection to the control board, thermal limit, or contractor coil is open

What Is Error 158 on Trane Thermostat?

Code 158 might indicate that the evaporator is too cold. Check the coil for icing – you’ll see this error if the element’s temperature drops below 32 F.

The two main things that will cause the coil to freeze are low airflow and a low level of refrigerant.

Check the air filters and make sure that nothing is blocking the vents. If you feel like the refrigerant level is too low, then you would have to call a professional to deal with the issue.

How Do You Clear a Trane Error Code?

You can easily clear the code by resetting the system. Flip the circuit breaker, wait for about a minute, and then turn the system back on.

If this trick didn’t clear the code, then calling an HVAC expert might be the best decision.

How Do You Reset a Trane Thermostat?

For XL824/850/1050 wireless thermostats:

  1. Make sure that the HVAC system is off.
  2. Press ‘menu’ on the thermostat screen.
  3. Select ‘settings’ and ‘reboot’.
  4. Press ‘yes’ and give the system quite a few minutes, so that it can reset.

For other thermostat models:

  1. Make sure that the HVAC system is off.
  2. Go to the breaker box and locate the switch that is wired to the thermostat.
  3. Flip the switch to the OFF position.
  4. Wait for half a minute.
  5. Flip the switch back to the ON position.
  6. Give the system some time.

Read: Why Furnace Not Responding To Thermostat?

Does Trane Thermostat Have Batteries?

Trane has a lot of different thermostats. Some of them are battery-operated, while others are connected directly to the grid.

If you have an 800 series Trane thermostat, for example, then you’re going to need to replace the AAA batteries once a year.

Fact: battery-operated wall thermostats, in general, use 3V button-style lithium batteries or AA, AAA alkaline batteries.

How Do You Troubleshoot a Trane Thermostat?

Try adjusting the temperature on the thermostat. If the device does not respond, then you can try:

  • Resetting the thermostat
  • Changing the batteries (if you have a battery-operated device)
  • Cleaning off the dirt and dust

Read: Temperature Thermostat Problems

Where Is the Reset Button on a Trane Heat Pump?

You can use the thermostat to turn the system off and back on or reset the unit at the breaker.

In any case, wait for around a minute before turning the system back on. It may take the unit up to 10 minutes to start operating.

Why Is My Trane AC Blinking Red?

A blinking red light can mean a lot of things. The answer is going to depend on the number of blinks and the speed.Slow flashing usually means that everything is ok. Any other flashing code indicates a malfunction in the system.