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 might occasionally run across a problem. With the digital display, Honeywell smart thermostats can show an error code that professional technicians use to understand 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 receive this error code if your home’s Wi-Fi connection did not present an IP address for the thermostat to connect to. This can take place if your router does not execute the Dynamic Host Configuration Protocol, or DHCP. This process automatically sends out the needed 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 has enabled DHCP. If it does, you may also need to power cycle the router and complete the initial setup process again with the thermostat. Completing this task should see to it that the DHCP is delivered and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears whenever the password for connecting to your home’s Wi-Fi router is not correct. After this error code is displayed 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 need to do to clear error e02 is ensure you’re typing 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 turning on despite being directed to. But this error code could also show up if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, induced by blocked airflow, can lead to this error code. And finally, you might see error code 40 if there’s a problem with the refrigerant, 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 regular operation. If you reset the thermostat and error code 40 reappears, it’s best to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If the Honeywell thermostat presents error code e43, it is unable to communicate with the router, and by extension the Wi-Fi. This might 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 around 30 seconds. The thermostat might also be disconnected if you have 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 detect the temperature outdoors and indoors. If a sensor fails, you may see 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 restart the thermostat, which should clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n can appear when the thermostat is unable to detect a heating or cooling unit. This might mean that the equipment itself is faulty and unable to connect with the thermostat. This can happen when the wiring is bad or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

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

Honeywell Thermostat Error e2

If you notice error code e2 appear on your Honeywell smart thermostat, it might mean a couple of different things. In some cases, one of the sensors used to detect the temperature isn’t operating properly. In other cases, it means the router was disconnected from its power source before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is a result of sensor failure, a technician should troubleshoot and replace the impacted sensor. If the problem stems from disconnected power, all you have to do is see to it that the router remains on over the course of the setup process.