Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is a great way to fine-tune how you use your HVAC system. But like any utility, you may occasionally run across a problem. With the digital display, Honeywell smart thermostats can display an error code that professional technicians will use to get a better sense of what's wrong. Here are several of the most common error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might encounter this error code in the event that your home’s Wi-Fi internet did not supply an IP address for the thermostat to hook up to. This can take place if the router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the necessary 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 can complete the DHCP. When it does, you usually also need to power cycle the router and repeat the initial setup process with your thermostat. Completing this task should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears whenever the password for communicating with your home’s Wi-Fi router is incorrect. Once this error code is displayed for 30 seconds, the thermostat’s digital display will automatically progress to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you have to do to solve error e02 is verify 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 detected a malfunction. Most often, this appears if the compressor isn’t turning on despite being directed to. But this error code could also show up if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, triggered by obstructed airflow, can display this error code. Lastly, you could experience error code 40 if there’s an issue with the coolant, 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 turn the thermostat off and on again and error code 40 reappears, it's time to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If a Honeywell thermostat presents error code e43, it is unable to communicate with the router, and by extension your Wi-Fi. This could 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 about 30 seconds. The thermostat may also be disconnected if you recently changed the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Thermostat Error e1

Thermostats utilize sensors to determine the temperature outdoors and indoors. If a sensor malfunctions, you may see error code e1 show up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A qualified technician can swap out the sensor and restart the thermostat, which should clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n can appear if the thermostat can’t connect to a heating or cooling unit. This can mean that the equipment itself is faulty and unable to communicate with the thermostat. This can happen when the wiring is defective or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

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

Honeywell Thermostat Error e2

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it can mean several different things. Sometimes, 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

In situations where the error code stems from sensor failure, a technician can troubleshoot and switch out the impacted sensor. Any time the problem originates from disconnected power, all you’ll have to do is verify the router remains on over the course of the setup process.