Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an excellent way to fine-tune how you use your HVAC system. But like any technology, you could sometimes run into a problem. With a digital display, Honeywell smart thermostats can show an error code that trained technicians can use to get a better sense of what's happening. Here are several of the most common error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might see this error code if your home’s Wi-Fi connection did not present an IP address for the thermostat to connect to. This can happen if a router fails to execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the necessary IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by verifying that your router can complete the DHCP. Assuming it does, you usually also need to power cycle the router and repeat the initial setup process with the thermostat. Doing so should see to it that the DHCP is sent and connects to your smart thermostat.

Honeywell Thermostat Error e02

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

How to Fix Honeywell Thermostat Error e02

All you have to do to clear error e02 is ensure you’re entering the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is informed that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most commonly, this happens if the compressor isn’t running despite being directed to. But this error code may also surface 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 render this error code. Lastly, you might encounter error code 40 if there’s something wrong 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 turn the thermostat off and on again and error code 40 reappears, it's time to get in touch with 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 the Wi-Fi. This could 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 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 give it.

Honeywell Thermostat Error e1

Thermostats utilize sensors to determine the temperature outdoors and indoors. If a sensor fails, you could see error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A trained technician can swap out the sensor and reset the thermostat, which should resolve error code e1.

Honeywell Thermostat Error 11n

Error code 11n could appear in situations where the thermostat is unable to recognize a heating or cooling unit. This may mean that the equipment itself is faulty and unable to connect with the thermostat. This sometimes happens when the wiring is bad 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 poor electrical connection. When the wiring on your type of HVAC system is bad, the technician can replace it. When the thermostat itself is the problem, it should probably be replaced.

Honeywell Thermostat Error e2

If you see error code e2 show up on your Honeywell smart thermostat, it can mean several different things. Sometimes, one of the sensors responsible for detecting the temperature isn’t working correctly. In other instances, it means the router was disconnected from the outlet before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician will troubleshoot and switch out the damaged sensor. When the problem stems from disconnected power, all you have to do is make sure the router remains on throughout the setup process.