A Honeywell smart thermostat is an excellent way to fine-tune how you use your heating and cooling. But like any utility, you could occasionally run into a problem. With its digital display, Honeywell smart thermostats can show an error code that certified technicians use to understand what's wrong. Here are some of the most common error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You may see this error code in the event that your home’s Wi-Fi internet did not supply an IP address for the thermostat to connect to. This can take place if your router fails to perform the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the needed IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

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

Error Code e02 for Honeywell Thermostats

Error code e02 is displayed when the password for accessing your home’s Wi-Fi router was incorrect. After 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 need to do to clear error e02 is make sure you’re entering the correct Wi-Fi password when setting up the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can pop up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most commonly, this occurs once the compressor isn’t running despite being instructed to. But this error code can also surface if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, induced by poor airflow, can render this error code. Finally, you may 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 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 best to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If the Honeywell thermostat presents error code e43, it is failing to communicate with the router, and by extension the Wi-Fi. This can 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 might also be disconnected if you’ve recently changed the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Error Code e1

Thermostats use sensors to determine the temperature outdoors and indoors. If a sensor malfunctions, you might see error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A trained technician can change out the sensor and reset the thermostat, which should take care of error code e1.

Error Code 11n for Honeywell Thermostats

Error code 11n may appear if the thermostat is unable to detect a heating or cooling unit. This can 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 find out if there’s a poor electrical connection. In situations where the wiring on your specific HVAC equipment is bad, the technician can replace it. When the thermostat itself is the source of the error code, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you see error code e2 pop up on your Honeywell smart thermostat, it can mean a couple of 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 power before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code stems from sensor failure, a technician can troubleshoot and switch out the damaged sensor. If the problem stems from disconnected power, all you have to do is see to it that the router stays on throughout the setup process.