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 across a problem. With its digital display, Honeywell smart thermostats can provide an error code that trained technicians can use to get a better sense of what's wrong. Here are several of the most common error codes you might see on your Honeywell smart thermostat.

Error Code e42 for Honeywell Thermostats

You can receive this error code if your home’s Wi-Fi internet did not provide an IP address for the thermostat to hook up to. This can take place if your router does not execute the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the necessary IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router has enabled DHCP. If it does, you might also have to power cycle the router and perform the setup process again with the thermostat. This should ensure the DHCP is delivered and connects to your smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 is displayed whenever the password for accessing your home’s Wi-Fi router is not correct. Once this error code has appeared 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 solve 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 pop up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most commonly, this occurs when the compressor isn’t working despite being directed to. But this error code could also appear if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, induced by blocked airflow, can lead to this error code. And finally, you may encounter 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 inspect 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.

Error Code e43 for Honeywell Thermostats

If the Honeywell thermostat presents error code e43, it is failing to 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

Restart the router by unplugging it and leaving it that way for around 30 seconds. The thermostat could 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 determine the temperature outdoors and indoors. If a sensor breaks down, you may notice error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A skilled technician can change out the sensor and reboot the thermostat, which should resolve error code e1.

Honeywell Thermostat Error 11n

Error code 11n may appear if the thermostat can’t detect 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 bad or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can use a voltmeter to determine if there’s a faulty electrical connection. When the wiring on your specific HVAC equipment is bad, the technician can replace it. If the thermostat itself is the source of the error code, it should probably be replaced.

Honeywell Error Code e2

If you see error code e2 show up on your Honeywell smart thermostat, it can mean a few different things. In some cases, one of the sensors used to detect the temperature isn’t operating properly. Other times, it means the router was disconnected from power before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is a result of sensor failure, a technician will troubleshoot and switch out the affected sensor. When the problem stems from disconnected power, all you have to do is make sure the router stays on during the setup process.