Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an excellent way to optimize how you use your heating and cooling. But like any technology, you could sometimes run across a problem. With the digital display, Honeywell smart thermostats can provide an error code that trained technicians can use to figure out what's happening. Here are some of the most known error codes you could 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 with. This can occur if the router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This function automatically transmits the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by making sure that your router has enabled DHCP. If it does, you may also have to power cycle the router and complete the initial setup process again with your thermostat. This should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears when 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 automatically transitions to the Wi-Fi setup screen so you can try the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to solve error e02 is ensure you’re putting in the correct Wi-Fi password when configuring 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 identified a malfunction. Most often, this occurs if the compressor isn’t turning on despite being directed to. But this error code can also surface if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, triggered by blocked airflow, can render this error code. Finally, you may experience error code 40 if there’s something wrong with the refrigerant, 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 ordinary operation. If you reset the thermostat and error code 40 reappears, you should try to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat shows error code e43, it can’t 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 the wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

Reboot the router by unplugging it and leaving it that way for about 30 seconds. The thermostat could also be disconnected if you’ve recently switched the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Thermostat Error e1

Thermostats employ sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you might notice error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n can appear if the thermostat can’t recognize 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 defective or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can employ a voltmeter to assess if there’s a poor electrical connection. In situations where the wiring on your existing HVAC equipment is bad, the technician can replace it. When 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 several different things. For example, one of the sensors that detects the temperature isn’t operating properly. In other cases, it means the router was disconnected from its power source before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code is caused by sensor failure, a technician can troubleshoot and switch out the impacted sensor. If the problem comes from disconnected power, all you'll need to do is see to it that the router remains on throughout the setup process.