A Honeywell smart thermostat is an easy way to better manage how you use your heating and cooling. But like any utility, you could occasionally run across a problem. With a 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 common error codes you might see on your Honeywell smart thermostat.

Error Code e42 for Honeywell Thermostats

You can see this error code in the event that your home’s Wi-Fi internet did not provide an IP address for the thermostat to hook up to. This can happen if your router doesn't execute the Dynamic Host Configuration Protocol, or DHCP. This process automatically supplies the needed 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 verifying that your router can complete the DHCP. When it does, you usually also need to power cycle the router and perform the setup process again with your thermostat. This should ensure the DHCP is delivered and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs whenever the password for communicating with your home’s Wi-Fi router is not correct. After this error code has appeared 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'll need to do to clear error e02 is make sure you’re putting in the correct Wi-Fi password when configuring the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can appear when the thermostat is informed that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most commonly, this occurs if the compressor isn’t working despite being instructed to. But this error code can also surface if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, caused by poor airflow, can display this error code. Lastly, you could see 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 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, it’s best to get a hold of an experienced technician.

Honeywell Error Code e43

If the Honeywell thermostat shows error code e43, it is unable to communicate with the router, and by extension your Wi-Fi. This might 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 have recently updated the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Error Code e1

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

How to Fix Honeywell Thermostat Error e1

A skilled technician can swap out 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 recognize a heating or cooling unit. This can mean that the equipment itself is defective and unable to communicate with the thermostat. This can happen when the wiring is damaged or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can employ a voltmeter to find out if there’s a faulty electrical connection. In situations where the wiring on your existing HVAC equipment is bad, the technician can replace it. If the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Error Code e2

If you see error code e2 pop up on your Honeywell smart thermostat, it could mean several different things. For example, one of the sensors responsible for detecting the temperature isn’t operating correctly. Other times, it means the router was disconnected from the outlet before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician should troubleshoot and switch out the impacted sensor. When the problem originates from disconnected power, all you have to do is verify the router remains on over the course of the setup process.