A Honeywell smart thermostat is an easy way to fine-tune how you use your HVAC system. But like any technology, you could occasionally experience a problem. With the digital display, Honeywell smart thermostats can display an error code that certified technicians use to understand what's going on. Here are several of the most known error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can receive this error code when your home’s Wi-Fi connection did not supply an IP address for the thermostat to connect with. This can occur if the router does not execute the Dynamic Host Configuration Protocol, or DHCP. This process automatically supplies the necessary IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by making sure that your router is enabled for DHCP. If it does, you usually also need to power cycle the router and repeat the initial setup process with the thermostat. Completing this task should see to it that the DHCP is sent and connects to your smart thermostat.

Error Code e02 for Honeywell Thermostats

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

How to Fix Honeywell Thermostat Error e02

All you need to do to resolve error e02 is verify you’re entering the correct Wi-Fi password when configuring the thermostat.

Error Code 40 for Honeywell Thermostats

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 appears once the compressor isn’t turning on despite being directed to. But this error code could also show up if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, triggered by poor airflow, can display this error code. And finally, you might 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 regular operation. If you reset the thermostat and error code 40 reappears, you should try to contact an experienced technician.

Honeywell Thermostat Error e43

If a Honeywell thermostat shows error code e43, it is unable to communicate with the router, and by extension the Wi-Fi. This could 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

Reboot 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 create for it.

Error Code e1 for Honeywell Thermostats

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

How to Fix Honeywell Thermostat Error e1

A qualified technician can replace the sensor and restart the thermostat, which should clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n can appear if the thermostat is unable to connect to a heating or cooling unit. This might mean that the equipment itself is defective and unable to connect 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 professional technician can utilize a voltmeter to assess if there’s a bad electrical connection. When the wiring on your specific HVAC system is bad, the technician can replace it. If the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you notice error code e2 pop up on your Honeywell smart thermostat, it can mean a couple of different things. Sometimes, one of the sensors that detects the temperature isn’t working like it should. In other cases, it means the router was disconnected from its power source before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician can troubleshoot and swap out the impacted sensor. When the problem originates from disconnected power, all you have to do is see to it that the router remains on throughout the setup process.