Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is a great way to fine-tune how you use your home comfort system. But like any technology, you might occasionally run into a problem. With its digital display, Honeywell smart thermostats can show an error code that trained technicians can use to figure out what's happening. Here are several of the most likely error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might receive this error code when your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect with. This can happen if the router doesn't execute the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the necessary IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by verifying that your router is enabled for DHCP. Assuming it does, you usually also have 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 delivered and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 occurs whenever the password for connecting to your home’s Wi-Fi router was 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 try to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you have to do to resolve error e02 is verify you’re typing the correct Wi-Fi password when setting up 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 identified a malfunction. For the most part, this happens when the compressor isn’t turning on despite being directed to. But this error code could also surface if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, triggered by poor airflow, can render this error code. And finally, you may see 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 contact an experienced technician.

Honeywell Error Code e43

If the Honeywell thermostat displays error code e43, it is unable 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 your wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

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

Honeywell Error Code e1

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

How to Fix Honeywell Thermostat Error e1

A trained technician can change out the sensor and reset the thermostat, which should resolve error code e1.

Honeywell Error Code 11n

Error code 11n can appear when the thermostat is unable 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 qualified technician can use a voltmeter to assess if there’s a bad electrical connection. When the wiring on your specific HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Error Code e2

If you see error code e2 appear on your Honeywell smart thermostat, it could mean a couple of different things. Sometimes, one of the sensors used to detect the temperature isn’t working correctly. 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

When the error code stems from sensor failure, a technician can troubleshoot and replace the impacted sensor. If the problem comes from disconnected power, all you have to do is see to it that the router remains on during the setup process.