16 Trane Thermostat Codes – Reliable Guide

Any thermostat will try to tell you that there is something wrong with the actual device or the HVAC system through an error code.

Trane thermostat codes will either be displayed in the corner of the screen, or the error will be alternating with the time. Consult the owner’s manual to find out what the fault code means. We’ve listed the most common codes below. In a lot of cases, the error code can be cleared by a simple reset.

Trane Thermostat Codes

Different Trane thermostat models will have different error codes. Some will simply display two or three digits, while others (like the Trane touchscreen thermostat) will show an ‘E’ and a digit.

Consult the owner’s manual to find out what the error code means. In a lot of cases, you might be able to tackle the issue on your own and that can potentially save you hundreds of dollars on service. 

digital thermostat

Read: How To Override A Trane Thermostat?

Trane Thermostat Codes List

The error code will appear at the bottom of the display. If you have a programmable thermostat, the code will be alternating with the time on the display.

Error CodeDescription
E0A thermistor error – the reading is out of range (less than 14 F or greater than 122 F)
E3Permanent data error
E4Input voltage is out of range (lower than 18VAC or higher than 34 VAC)
E5RTC error
E7Memory error

Error Code 79

The low-pressure switch is open in the outdoor unit. This can happen, if:

You can try resetting the thermostat and the HVAC unit. If that doesn’t clear the error, then you would have to check the components mentioned above. 

Read: Trane Error Code 126 – Troubleshooting Guide

Error Code 91

Error code 91 indicates a loss of communication between the thermostat and the HVAC equipment. Such a code will usually appear after a power-related issue.

In general, it should take the thermostat up to 30 minutes to re-establish the contact and start working again. If the error code did not go away, either the thermostat or the circuit board might be faulty. 

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Error Code 126

Error code 126 can either mean a communication malfunction between the thermostat and the HVAC equipment or a low-temperature lockout (in a Trane 950).

In both cases, you can try resetting the system. 

Read: Trane Furnace Error Codes -Troubleshooting Guide

Error Code 158

If the thermostat is showing fault code 158, it means that the evaporator coil is too cold (its temperature dropped below 32 F).

There are two main things that can cause coil freezing:

  1. Insufficient airflow (replacing the filter should fix the issue)
  2. A low level of refrigerant

What Does E1 Mean on Trane Mini Split?

Generally, an E1 error indicates a communication malfunction between the mini split’s outdoor and indoor unit. Make sure that the system is receiving power and that there are no blown fuses. 

Check whether the linking cable between the units is well connected. Also, ensure that the core wires are well-insulated. 

You might have to reconnect the cable or replace it with a new one. 

Read: Why Does Thermostat Say Return?

How Do I Fix the E2 Code on My Trane Thermostat?

open thermostat

Another one of the Trane thermostat codes you might encounter is E2. An E2 error code indicates a sensor failure shutdown. Such an issue might require service. 

What Does E4 Mean on a Trane Thermostat?

An E4 error code means that the input voltage is out of range. It looks like it is either lower than 18VAC or higher than 32 VAC.

You might have to check the thermostat’s voltage. Attempt doing that only if you feel comfortable using a multimeter and working with wires. 

Trane Comfortlink Error Codes

The Trane Comfortlink thermostat will display ‘Err’ on the screen when displaying an error code. You will also see a red light appear in the top right corner.

To find out what the error code indicates, contact your Trane dealer or refer to the Alert Code Addendum

Trane Comfortlink II Error Code 22

Code 22 means ‘soft lockout’. This could happen due to flame loss or unsuccessful ignition attempts. 

You can try to clean the pilot assembly mounts and the burners. Simply resetting the thermostat might also help, in some cases. 

Trane Comfortlink II Error Code 90

Error code 90 means that the device is not recognizing the equipment

At times, all you would have to do is turn off the outdoor and indoor units, turn them back on, and give the system a few minutes to re-establish the communication. 

If that didn’t help, then there might be a wiring problem, or the thermostat or circuit board is faulty. 

Trane Comfortlink II Error Code 126

On a Trane Comfortlink thermostat, an error 126 indicates a low-temperature lockout. The system might shut down if the outside temperature is too low.

Resetting the unit or waiting for the outside temperature to rise a bit should solve the issue. 

Read: Why Is House Thermostat Reading The Wrong Temperature?

Trane Comfortlink II XL1050 Error Codes

The alerts on your Trane Comfortlink II XL1050 thermostat can be found within the diagnostic screen. You can select the alert and get additional information about it.

To enter the diagnostic screen, navigate to the service menu and then choose ‘diagnostics’. 

All the alerts will be categorized by severity – critical, major, and normal. The former might require a service call.

What Does System Idle Mean on Thermostat?

System idle means that the equipment is not on at the moment, but it will start functioning once the 3-5 minutes wait period is over

This usually happens when you switch between heating and cooling or when you turn the system off and on too fast. 

How Do You Unlock a Trane Air Fi Thermostat?

To unlock your Trane thermostat, you should:

  1. Press the + and – buttons at the same time.
  2. Hold the buttons down for around 5 seconds and release them.
  3. The thermostat is unlocked.
Trane thermostat codes on display

How Do You Clear Trane Thermostat Codes?

Once you have taken care of the issue that made the error code appear in the first place, you can perform a system reset – this will usually clear the code.

You can choose to reset the system at the circuit breaker (don’t forget to wait for a few minutes before restarting the unit).

How Do You Troubleshoot a Trane Thermostat?

Here are the most common troubleshooting tips, when it comes to dealing with a Trane thermostat:

  • Replace the batteries
  • Check the house’s main power source (make sure that the breaker had not tripped and that there are no blown fuses)
  • Check the thermostat settings
  • Clean the device (remove the cover and gently brush it to get rid of the dust)
  • Replace the HVAC system’s air filter
  • Perform a thermostat calibration with the help of a thermometer
  • Reset the device
Thermostat batteries

How Do You Reset a Trane Thermostat?

During the process of troubleshooting your Trane thermostat codes, you will sometimes need to reset the code manually.

On some wireless thermostat models, you can try resetting the device by pressing ‘menu’, selecting ‘settings’, and tapping ‘reboot’.

All the other models can be reset by turning the thermostat on and off at the circuit breaker. 

Does a Trane Unit Have a Reset Button?

In Trane furnaces, the reset button is usually located right next to the blower wheel and blower motor.

How Do I Reset My Trane AC Unit?

In air conditioning units, the reset button can be generally found along the bottom edge of the unit. It might also be located inside the equipment, behind the service panel.

If you can’t find the reset button, you can always reset the cooling unit at the circuit breaker.

Do Trane Thermostats Have Batteries?

Not all Trane thermostats are battery-operated, some will get hardwired directly into your wall. 

The devices that do come with a battery compartment might not need the batteries to operate – they can act as a backup power source in case of an outage.

Why Is My Trane Thermostat Not Heating?

  • The circuit breaker had tripped
  • The thermostat is set too low
  • The thermostat is not calibrated properly
  • The air filters are dirty
  • The pilot light is out or the gas is turned off

Final Thoughts

Now you have a list of the most common Trane thermostat codes and how to determine what they mean. Be sure to consult your particular thermostat’s user manual for further information. As new models are produced, they will undoubtedly employ varying functions and therefore different codes.