A Honeywell smart thermostat is an easy way to fine-tune how you use your HVAC system. But like any technology, you could sometimes run into a problem. With its digital display, Honeywell smart thermostats can show an error code that professional technicians will use to figure out what's happening. Here are a few of the most known error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can encounter this error code when your home’s Wi-Fi internet did not provide an IP address for the thermostat to connect to. This can occur if the router fails to execute the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the needed IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by verifying that your router can complete the DHCP. If it does, you usually also have to power cycle the router and complete the initial setup process again with your thermostat. Completing this task should see to it that the DHCP is sent and connects to your smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 appears whenever the password for connecting to your home’s Wi-Fi router was incorrect. After this error code appears 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 need to do to clear error e02 is make sure you’re entering 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. Most commonly, this happens when the compressor isn’t turning on despite being directed 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 poor airflow, can lead to this error code. Finally, you could encounter error code 40 if there’s a problem with the refrigerant, the outdoor uni