A Honeywell smart thermostat is a great way to optimize how you use your home comfort system. But like any mechanical system, you may occasionally experience a problem. With its digital display, Honeywell smart thermostats can display an error code that certified technicians can use to get a better sense of what's happening. Here are a few of the most known error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might receive this error code if your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect with. This can take place if your router does not complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically sends out the needed IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by confirming that your router is enabled for DHCP. Assuming it does, you usually also need to power cycle the router and repeat the initial setup process with the thermostat. This should ensure the DHCP is transmitted and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 appears when the password for connecting to your home’s Wi-Fi router was incorrect. 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 to enter the password again.

How to Fix Honeywell Thermostat Error e02

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

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is informed that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most often, this happens if the compressor isn’t working despite being instructed to. But this error code may also surface if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, induced by blocked airflow, can display this error code. Finally, you might 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 check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for normal operation. If you restart the thermostat and error code 40 reappears, it’s best to get in touch with an experienced technician.

Error Code e43 for Honeywell Thermostats

If your Honeywell thermostat shows error code e43, it is failing to communicate with the router, and by extension your Wi-Fi. This may 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 might also be disconnected if you have 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 use sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you could notice error code e1 show up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Error Code 11n

Error code 11n can appear when the thermostat is unable to recognize a heating or cooling unit. This can mean that the equipment itself is defective and unable to connect with the thermostat. This sometimes happens when the wiring is bad or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

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

Error Code e2 for Honeywell Thermostats

If you see error code e2 pop up on your Honeywell smart thermostat, it might mean a couple of different things. In some cases, one of the sensors responsible for detecting the temperature isn’t functioning like it should. 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 is caused by sensor failure, a technician should troubleshoot and switch out the impacted sensor. Any time the problem originates from disconnected power, all you have to do is see to it that the router remains on over the course of the setup process.