Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an easy way to optimize how you use your home comfort system. But like any technology, you may sometimes run into a problem. With the digital display, Honeywell smart thermostats can display an error code that trained technicians can use to figure out what's going on. Here are several of the most known error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can receive this error code if your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect with. This can happen if the router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This process automatically sends out the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by making sure that your router is enabled for DHCP. When it does, you usually also have to power cycle the router and perform the setup process again with the thermostat. Doing so should see to it that the DHCP is delivered and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed if the password for communicating with your home’s Wi-Fi router was incorrect. Once this error code is displayed for 30 seconds, the thermostat’s digital display automatically transitions to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you have to do to clear error e02 is make sure you’re typing the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most often, this appears when the compressor isn’t running despite being directed to. But this error code may also appear if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, caused by poor airflow, can lead to this error code. Finally, you might encounter error code 40 if there’s something wrong with the refrigerant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for regular operation. If you restart the thermostat and error code 40 reappears, you should try to contact an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat shows error code e43, it is unable to communicate with the router, and by extension your Wi-Fi. This may happen if the router’s ethernet cable isn’t plugged in or it isn’t communicating with your wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

Reset the router by unplugging it and leaving it that way for around 30 seconds. The thermostat may also be disconnected if you recently changed the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Thermostat Error e1

Thermostats utilize sensors to determine the temperature outdoors and indoors. If a sensor fails, you may notice error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A skilled technician can change out the sensor and reset the thermostat, which should clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n may appear when the thermostat is failing to recognize a heating or cooling unit. This might mean that the equipment itself is defective and unable to maintain a connection to the thermostat. This sometimes happens when the wiring is defective or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can employ a voltmeter to find out if there’s a faulty electrical connection. In situations where the wiring on your type of HVAC system is bad, the technician can replace it. When the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you notice error code e2 appear on your Honeywell smart thermostat, it might mean a few different things. In some cases, one of the sensors used to detect the temperature isn’t functioning properly. In other cases, it means the router was disconnected from the outlet before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is a result of sensor failure, a technician will troubleshoot and swap out the damaged sensor. Any time the problem stems from disconnected power, all you’ll have to do is make sure the router stays on over the course of the setup process.