Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is an excellent way to fine-tune how you use your home comfort system. But like any utility, you could sometimes experience a problem. With a digital display, Honeywell smart thermostats can show an error code that certified technicians will use to figure out what's wrong. Here are some of the most common error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You may encounter this error code when your home’s Wi-Fi connection did not present an IP address for the thermostat to connect with. This can occur if the router does not complete the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router has enabled DHCP. If it does, you might 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 the smart thermostat.

Honeywell Error Code 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 automatically transitions to the Wi-Fi setup screen so you can try to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to solve error e02 is ensure you’re typing the correct Wi-Fi password when configuring the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can pop up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most often, this happens if the compressor isn’t turning on despite being instructed to. But this error code could also surface if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, triggered by blocked airflow, can display this error code. And finally, you might encounter error code 40 if there’s a problem with the refrigerant, 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, you should try to contact an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat displays error code e43, it is unable to communicate with the router, and by extension your Wi-Fi. This may 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

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 updated the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Thermostat Error e1

Thermostats employ sensors to determine the temperature outdoors and indoors. If a sensor fails, you may 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 reboot the thermostat, which should resolve error code e1.

Honeywell Error Code 11n

Error code 11n may appear if the thermostat is unable to connect to a heating or cooling unit. This can mean that the equipment itself is defective and unable to maintain a connection to the thermostat. This can happen when the wiring is defective or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can use 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. If the thermostat itself is the source of the error code, it will likely have to be replaced.

Error Code e2 for Honeywell Thermostats

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it could mean several different things. In some cases, one of the sensors responsible for detecting 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 caused by sensor failure, a technician should troubleshoot and switch out the damaged sensor. If the problem originates from disconnected power, all you'll need to do is make sure the router stays on during the setup process.