A Honeywell smart thermostat is an excellent way to fine-tune how you use your HVAC system. But like any technology, you might occasionally experience a problem. With the digital display, Honeywell smart thermostats can display an error code that professional technicians use to understand what's wrong. Here are several of the most known error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You may encounter this error code in the event that your home’s Wi-Fi internet did not provide an IP address for the thermostat to connect with. This can take place if the router does not execute the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the required IP address for your thermostat to link up.

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 need to power cycle the router and repeat the initial setup process with your thermostat. Completing this task should see to it that the DHCP is delivered and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 appears when the password for accessing your home’s Wi-Fi router is incorrect. When this error code has appeared for 30 seconds, the thermostat’s digital display automatically transitions to the Wi-Fi setup screen so you can try to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to solve 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 pop up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has identified a malfunction. For the most part, this happens if the compressor isn’t turning on despite being directed to. But this error code may also show up if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, caused by blocked airflow, can render this error code. Lastly, you may experience 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 check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for normal operation. If you reset the thermostat and error code 40 reappears, it’s best to get in touch with an experienced technician.

Honeywell Thermostat Error e43

If a Honeywell thermostat shows error code e43, it is failing to communicate with the router, and by extension your Wi-Fi. This can 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 a short period. The thermostat may also be disconnected if you’ve 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 identify the temperature outdoors and indoors. If a sensor fails, you may notice error code e1 appear 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 Error Code 11n

Error code 11n may appear in situations where 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 sometimes happens when the wiring is damaged or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can utilize a voltmeter to determine if there’s a poor electrical connection. If the wiring on your existing HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the issue, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you see error code e2 show up on your Honeywell smart thermostat, it might mean a couple of different things. In some cases, one of the sensors that detects the temperature isn’t working correctly. In other cases, it means the router was disconnected from power before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is a result of sensor failure, a technician can troubleshoot and replace the affected sensor. Any time the problem originates from disconnected power, all you’ll have to do is see to it that the router stays on during the setup process.