Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is an excellent way to optimize how you use your heating and cooling. But like any utility, you might occasionally experience a problem. With a digital display, Honeywell smart thermostats can provide an error code that professional technicians will use to understand what's wrong. Here are some of the most likely error codes you might see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can see this error code when your home’s Wi-Fi internet did not supply an IP address for the thermostat to hook up to. This can occur if the router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the needed IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by confirming that your router can complete the DHCP. Assuming it does, you usually also have to power cycle the router and complete the initial setup process again with the thermostat. Completing this task should ensure the DHCP is delivered and connects to your smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 occurs if the password for communicating with your home’s Wi-Fi router was incorrect. After this error code is displayed for 30 seconds, the thermostat’s digital display should automatically transition to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to solve error e02 is make sure you’re putting in the correct Wi-Fi password when setting up the thermostat.

Honeywell Error Code 40

Error code 40 can pop up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most often, this occurs if the compressor isn’t turning on despite being directed to. But this error code may also appear if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, caused by poor airflow, can render this error code. Lastly, you could encounter 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 examine the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for regular operation. If you restart the thermostat and error code 40 reappears, it’s best to get in touch with an experienced technician.

Honeywell Error Code e43

If the 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

Reboot the router by unplugging it and leaving it that way for a short period. The thermostat could also be disconnected if you recently updated the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Thermostat Error e1

Thermostats use sensors to identify the temperature outdoors and indoors. If a sensor malfunctions, you could 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 reset the thermostat, which should resolve error code e1.

Error Code 11n for Honeywell Thermostats

Error code 11n can appear in situations where the thermostat can’t detect a heating or cooling unit. This may 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 professional technician can employ a voltmeter to find out if there’s a bad electrical connection. If the wiring on your specific HVAC equipment is bad, the technician can replace it. If the thermostat itself is the problem, it should probably be replaced.

Honeywell Error Code e2

If you see error code e2 show up on your Honeywell smart thermostat, it could mean a few different things. Sometimes, one of the sensors responsible for detecting the temperature isn’t functioning properly. In other instances, it means the router was disconnected from its power source before the thermostat finished 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 damaged sensor. Any time the problem originates from disconnected power, all you’ll have to do is verify the router stays on throughout the setup process.