A Honeywell smart thermostat is an excellent way to fine-tune how you use your home comfort system. But like any mechanical system, you might sometimes run into a problem. With a digital display, Honeywell smart thermostats can provide an error code that certified technicians use to understand what's going on. Here are some of the most common error codes you may see on your Honeywell smart thermostat.

Error Code e42 for Honeywell Thermostats

You may see this error code when your home’s Wi-Fi connection did not present an IP address for the thermostat to hook up to. This can take place if the router fails to perform the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by verifying that your router is enabled for DHCP. When it does, you usually also have to power cycle the router and complete the initial setup process again with your thermostat. Completing this task should see to it that the DHCP is sent and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed when the password for accessing your home’s Wi-Fi router is not correct. When this error code appears 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 verify you’re putting in the correct Wi-Fi password when configuring the thermostat.

Honeywell Thermostat Error 40

Error code 40 can show up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most commonly, this happens once the compressor isn’t turning on despite being directed to. But this error code may also surface if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, induced by blocked airflow, can display this error code. Lastly, you could experience error code 40 if there’s an issue with the refrigerant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can examine the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for ordinary operation. If you turn the thermostat off and on again and error code 40 reappears, it's time to get in touch with an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat shows error code e43, it can’t communicate with the router, and by extension the 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

Restart the router by unplugging it and leaving it that way for about 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 provide it.

Error Code e1 for Honeywell Thermostats

Thermostats use sensors to identify the temperature outdoors and indoors. If a sensor malfunctions, you might see error code e1 appear 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 resolve error code e1.

Error Code 11n for Honeywell Thermostats

Error code 11n could appear when the thermostat is failing to recognize a heating or cooling unit. This can mean that the equipment itself is malfunctioning and unable to communicate with the thermostat. This can happen when the wiring is damaged or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A qualified 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 equipment is bad, the technician can replace it. In situations where the thermostat itself is the issue, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 show up on your Honeywell smart thermostat, it might mean a few different things. For example, one of the sensors used to detect the temperature isn’t operating correctly. In other instances, it means the router was disconnected from its power source before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is caused by sensor failure, a technician will troubleshoot and switch out the affected sensor. Any time the problem comes from disconnected power, all you’ll have to do is see to it that the router stays on during the setup process.