A Honeywell smart thermostat is an easy way to fine-tune how you use your HVAC system. But like any utility, you could sometimes experience a problem. With the digital display, Honeywell smart thermostats can show an error code that certified technicians use to get a better sense of what's wrong. Here are a few of the most common error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can see this error code when your home’s Wi-Fi internet did not present an IP address for the thermostat to hook up to. This can happen if the router fails to complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the required 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 is enabled for DHCP. Assuming it does, you might also need to power cycle the router and complete the initial setup process again with your thermostat. Doing so should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Error Code e02

Error code e02 is displayed whenever the password for connecting to your home’s Wi-Fi router is 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 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 typing the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has recognized a malfunction. For the most part, this appears if the compressor isn’t turning on despite being instructed to. But this error code could also surface if power is shut off from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, induced by blocked airflow, can display this error code. And finally, you might encounter error code 40 if there’s a problem with the coolant, 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 reset the thermostat and error code 40 reappears, you should try to get in touch with an experienced technician.

Error Code e43 for Honeywell Thermostats

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

Restart the router by unplugging it and leaving it that way for around 30 seconds. The thermostat could also be disconnected if you have recently switched the password or the Wi-Fi’s SSID, which is the name you provide 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 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n can appear when the thermostat can’t recognize a heating or cooling unit. This might mean that the equipment itself is defective and unable to maintain a connection to 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 licensed technician can employ a voltmeter to find out if there’s a faulty electrical connection. When 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 should probably be replaced.

Error Code e2 for Honeywell Thermostats

If you see error code e2 appear on your Honeywell smart thermostat, it could mean a few different things. Sometimes, one of the sensors that detects the temperature isn’t working like it should. Other times, it means the router was disconnected from the outlet before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is caused by sensor failure, a technician should troubleshoot and replace the damaged 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.