A Honeywell smart thermostat is an easy way to better manage how you use your HVAC system. But like any mechanical system, you might occasionally run across a problem. With the digital display, Honeywell smart thermostats can provide an error code that trained technicians will 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 Thermostat Error e42

You may receive this error code when your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect to. This can take place if your router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by making sure that your router can complete the DHCP. When it does, you might also have to power cycle the router and perform the setup process again with your thermostat. This should ensure the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears when the password for connecting to your home’s Wi-Fi router is not correct. Once 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 solve error e02 is verify you’re entering the correct Wi-Fi password when configuring the thermostat.

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is notified that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most often, this happens if the compressor isn’t working despite being instructed to. But this error code can also show up if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, caused by blocked airflow, can display this error code. Finally, you could experience error code 40 if there’s something wrong 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 restart the thermostat and error code 40 reappears, it's time to contact an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat shows error code e43, it is failing 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 the wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

Reboot the router by unplugging it and leaving it that way for around 30 seconds. The thermostat might also be disconnected if you’ve recently updated the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Thermostat Error e1

Thermostats utilize sensors to identify the temperature outdoors and indoors. If a sensor fails, you may notice error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n may appear if the thermostat is failing to detect a heating or cooling unit. This can mean that the equipment itself is malfunctioning 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 employ a voltmeter to determine if there’s a poor electrical connection. When the wiring on your specific HVAC system is bad, the technician can replace it. When the thermostat itself is the issue, it should probably be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it might mean a few different things. For example, one of the sensors used to detect the temperature isn’t operating like it should. 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 stems from sensor failure, a technician will troubleshoot and swap out the damaged sensor. Any time the problem comes from disconnected power, all you have to do is make sure the router remains on during the setup process.