Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is a great way to better manage how you use your home comfort system. But like any utility, you could occasionally run across a problem. With a digital display, Honeywell smart thermostats can show an error code that professional technicians use to figure out what's wrong. Here are a few of the most common error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can encounter this error code in the event that your home’s Wi-Fi connection did not supply an IP address for the thermostat to hook up to. This can occur if the router does not execute the Dynamic Host Configuration Protocol, or DHCP. This process automatically sends out 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 is enabled for DHCP. When it does, you usually also need to power cycle the router and perform the setup process again with the thermostat. Doing so should ensure the DHCP is delivered and connects to your smart thermostat.

Error Code e02 for Honeywell Thermostats

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 should automatically transition to the Wi-Fi setup screen so you can try to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you have to do to clear error e02 is verify you’re typing the correct Wi-Fi password when configuring the thermostat.

Honeywell Error Code 40

Error code 40 can show 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 running despite being instructed to. But this error code could also show up if power is shut off from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, triggered by blocked airflow, can render this error code. Lastly, you could see error code 40 if there’s an issue 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 ordinary operation. If you reset the thermostat and error code 40 reappears, you should try to get a hold of an experienced technician.

Honeywell Error Code e43

If a Honeywell thermostat presents error code e43, it is unable to communicate with the router, and by extension your 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 may also be disconnected if you recently switched the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Error Code e1

Thermostats utilize sensors to identify the temperature outdoors and indoors. If a sensor malfunctions, you might notice error code e1 show up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Error Code 11n for Honeywell Thermostats

Error code 11n may appear in situations where the thermostat is unable to detect a heating or cooling unit. This may mean that the equipment itself is faulty and unable to maintain a connection to the thermostat. This sometimes happens when the wiring is damaged or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A professional technician can employ a voltmeter to find out if there’s a poor electrical connection. If the wiring on your existing HVAC equipment is bad, the technician can replace it. In situations where the thermostat itself is the source of the error code, it will likely have to be replaced.

Honeywell Error Code e2

If you’ve noticed error code e2 appear on your Honeywell smart thermostat, it can mean several different things. For example, one of the sensors that detects the temperature isn’t functioning correctly. In other cases, it means the router was disconnected from power before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician should troubleshoot and replace the impacted sensor. Any time the problem stems from disconnected power, all you’ll have to do is see to it that the router remains on throughout the setup process.