A Honeywell smart thermostat is an excellent way to better manage how you use your home comfort system. But like any technology, you might occasionally run into a problem. With a digital display, Honeywell smart thermostats can display an error code that certified technicians use to figure out what's happening. Here are a few of the most common error codes you may see on your Honeywell smart thermostat.

Error Code e42 for Honeywell Thermostats

You may receive this error code if your home’s Wi-Fi internet did not present an IP address for the thermostat to hook up to. This can take place if a router doesn't execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the needed IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by verifying that your router has enabled DHCP. If it does, you may also need to power cycle the router and repeat the initial setup process with the thermostat. This should see to it that the DHCP is transmitted and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

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

How to Fix Honeywell Thermostat Error e02

All you'll need to do to resolve error e02 is verify you’re typing the correct Wi-Fi password when setting up the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can appear when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most often, this appears once the compressor isn’t working despite being directed to. But this error code could also show up if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, caused by blocked airflow, can lead to this error code. Lastly, you could encounter error code 40 if there’s a problem with the refrigerant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can inspect the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for normal operation. If you reset the thermostat and error code 40 reappears, it's time to get a hold of an experienced technician.

Honeywell Error Code e43

If the Honeywell thermostat presents error code e43, it is failing 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 the 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 might also be disconnected if you recently changed the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Error Code e1

Thermostats utilize sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you might see error code e1 show up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A skilled technician can replace the sensor and reboot the thermostat, which should take care of error code e1.

Honeywell Error Code 11n

Error code 11n can appear if the thermostat is failing to detect a heating or cooling unit. This might mean that the equipment itself is malfunctioning and unable to connect with 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 use a voltmeter to assess if there’s a faulty electrical connection. In situations where the wiring on your specific HVAC equipment is bad, the technician can replace it. In situations where the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you see error code e2 appear on your Honeywell smart thermostat, it could mean a few different things. For example, one of the sensors responsible for detecting the temperature isn’t operating 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

When the error code is a result of sensor failure, a technician should troubleshoot and switch out the affected sensor. If the problem originates from disconnected power, all you’ll have to do is verify the router remains on during the setup process.