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 experience a problem. With its digital display, Honeywell smart thermostats can provide an error code that professional technicians can use to figure out what's wrong. Here are some of the most likely error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can see this error code in the event that your home’s Wi-Fi internet did not present an IP address for the thermostat to hook up to. This can occur if a router does not perform the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the needed IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by confirming that your router has enabled DHCP. Assuming it does, you may also need to power cycle the router and repeat the initial setup process with your thermostat. Completing this task should see to it that the DHCP is sent and connects to your smart thermostat.

Honeywell Error Code e02

Error code e02 is displayed whenever the password for connecting to your home’s Wi-Fi router is not correct. Once this error code is displayed for 30 seconds, the thermostat’s digital display will automatically progress 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 ensure you’re entering the correct Wi-Fi password when setting up the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can show up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most often, this occurs once the compressor isn’t turning on despite being directed to. But this error code can also surface if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, caused by poor airflow, can lead to this error code. Lastly, you may 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 normal operation. If you reset the thermostat and error code 40 reappears, it's time to get in touch with an experienced technician.

Error Code e43 for Honeywell Thermostats

If your Honeywell thermostat presents error code e43, it can’t communicate with the router, and by extension your Wi-Fi. This can 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

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

Honeywell Error Code e1

Thermostats employ sensors to determine the temperature outdoors and indoors. If a sensor malfunctions, you might notice error code e1 turn up 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 clear error code e1.

Honeywell Error Code 11n

Error code 11n may appear if the thermostat is unable to recognize a heating or cooling unit. This might mean that the equipment itself is defective and unable to communicate with the thermostat. This sometimes happens 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 poor electrical connection. If the wiring on your existing HVAC system is bad, the technician can replace it. If the thermostat itself is the issue, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it could mean a few different things. For example, one of the sensors used to detect the temperature isn’t operating properly. Other times, it means the router was disconnected from power 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 will troubleshoot and replace the impacted sensor. If the problem stems from disconnected power, all you’ll have to do is make sure the router remains on throughout the setup process.