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

Honeywell Error Code e42

You might see this error code if your home’s Wi-Fi connection did not supply an IP address for the thermostat to hook up to. This can happen if the router fails to complete the Dynamic Host Configuration Protocol, or DHCP. This function automatically transmits the necessary IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router has enabled DHCP. When it does, you might also have to power cycle the router and repeat the initial setup process with the thermostat. Doing so should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears whenever the password for connecting to your home’s Wi-Fi router is not correct. After this error code has appeared for 30 seconds, the thermostat’s digital display should automatically transition to the Wi-Fi setup screen so you can try the password again.

How to Fix Honeywell Thermostat Error e02

All you have to do to clear error e02 is make sure you’re putting in the correct Wi-Fi password when configuring the thermostat.

Honeywell Error Code 40

Error code 40 can pop up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most often, this happens if the compressor isn’t working despite being instructed to. But this error code may also appear if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, induced by poor airflow, can display this error code. Finally, you might see error code 40 if there’s something wrong with the coolant, 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 regular operation. If you turn the thermostat off and on again and error code 40 reappears, you should try to get in touch with an experienced technician.

Honeywell Thermostat Error e43

If the Honeywell thermostat presents error code e43, it can’t communicate with the router, and by extension your Wi-Fi. This could 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

Reboot the router by unplugging it and leaving it that way for a short period. The thermostat could also be disconnected if you have recently switched the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Error Code e1

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

How to Fix Honeywell Thermostat Error e1

A trained technician can replace the sensor and reboot the thermostat, which should resolve error code e1.

Honeywell Error Code 11n

Error code 11n could appear if the thermostat can’t recognize a heating or cooling unit. This may mean that the equipment itself is faulty and unable to connect with the thermostat. This sometimes happens when the wiring is bad or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can use a voltmeter to determine if there’s a bad electrical connection. When the wiring on your type of HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the issue, it should probably be replaced.

Honeywell Thermostat Error e2

If you see error code e2 show up on your Honeywell smart thermostat, it could mean a couple of different things. For example, one of the sensors used to detect the temperature isn’t functioning correctly. In other cases, it means the router was disconnected from its power source before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is caused by sensor failure, a technician can troubleshoot and swap out the impacted sensor. If the problem stems from disconnected power, all you’ll have to do is make sure the router remains on throughout the setup process.