Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an easy way to optimize how you use your heating and cooling. But like any technology, you may occasionally run into a problem. With a digital display, Honeywell smart thermostats can provide an error code that professional technicians 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 may see this error code in the event that your home’s Wi-Fi connection did not supply an IP address for the thermostat to connect with. This can take place if your router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This process 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 is enabled for DHCP. Assuming it does, you might 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 your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs whenever the password for accessing your home’s Wi-Fi router is not correct. After this error code appears for 30 seconds, the thermostat’s digital display will automatically progress 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 show up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most often, this occurs once the compressor isn’t running despite being instructed to. But this error code could also show up 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 see error code 40 if there’s a problem 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 ordinary 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 your Honeywell thermostat presents error code e43, it is failing to communicate with the router, and by extension the Wi-Fi. This may 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

Restart the router by unplugging it and leaving it that way for about 30 seconds. The thermostat may also be disconnected if you’ve recently updated 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 notice error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n could appear in situations where the thermostat is unable to 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 bad or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A professional technician can utilize a voltmeter to determine if there’s a faulty electrical connection. When the wiring on your specific HVAC system is bad, the technician can replace it. When the thermostat itself is the source of the error code, it should probably be replaced.

Honeywell Thermostat Error e2

If you see error code e2 appear on your Honeywell smart thermostat, it can mean a few different things. For example, one of the sensors that detects the temperature isn’t working correctly. In other instances, it means the router was disconnected from its power source before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is a result of sensor failure, a technician should troubleshoot and switch out the affected sensor. When the problem stems from disconnected power, all you'll need to do is see to it that the router stays on during the setup process.