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 heating and cooling. But like any utility, you may sometimes run across a problem. With its digital display, Honeywell smart thermostats can provide an error code that trained technicians use to get a better sense of what's happening. Here are some of the most common error codes you may see on your Honeywell smart thermostat.

Honeywell Error Code e42

You may receive this error code in the event that your home’s Wi-Fi connection did not present an IP address for the thermostat to connect with. This can happen if a router fails to complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the necessary 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 is enabled for DHCP. If it does, you may also have 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 sent and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 is displayed if the password for communicating with your home’s Wi-Fi router is incorrect. Once this error code has appeared for 30 seconds, the thermostat’s digital display will automatically progress to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you need to do to resolve error e02 is ensure you’re entering the correct Wi-Fi password when configuring the thermostat.

Honeywell Thermostat Error 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. For the most part, this happens when the compressor isn’t running despite being directed to. But this error code can also surface if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, induced by poor airflow, can display this error code. Lastly, you might encounter 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 examine 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, it's time to get a hold of an experienced technician.

Error Code e43 for Honeywell Thermostats

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

Honeywell Thermostat Error e1

Thermostats utilize sensors to determine the temperature outdoors and indoors. If a sensor malfunctions, you could see 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 Thermostat Error 11n

Error code 11n can appear in situations where the thermostat is failing to recognize a heating or cooling unit. This can mean that the equipment itself is faulty 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 licensed technician can utilize a voltmeter to find out if there’s a faulty electrical connection. In situations where the wiring on your existing HVAC equipment is bad, the technician can replace it. When the thermostat itself is the issue, it should probably be replaced.

Honeywell Error Code e2

If you notice error code e2 appear on your Honeywell smart thermostat, it might mean several different things. For example, one of the sensors used to detect the temperature isn’t operating like it should. Other times, it means the router was disconnected from its power source before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code is caused by sensor failure, a technician can troubleshoot and replace the damaged sensor. If the problem stems from disconnected power, all you'll need to do is verify the router remains on over the course of the setup process.