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 heating and cooling. But like any mechanical system, you could occasionally run across a problem. With a digital display, Honeywell smart thermostats can show an error code that trained technicians can use to figure out what's happening. Here are a few of the most likely error codes you may see on your Honeywell smart thermostat.

Error Code e42 for Honeywell Thermostats

You might see this error code when your home’s Wi-Fi internet did not provide an IP address for the thermostat to hook up to. This can take place if your router fails to execute the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the required 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 have to power cycle the router and repeat the initial setup process with your thermostat. This should see to it that the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed if the password for connecting to your home’s Wi-Fi router is not correct. After 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 the password again.

How to Fix Honeywell Thermostat Error e02

All you need to do to clear error e02 is ensure 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. For the most part, this happens if the compressor isn’t working despite being instructed to. But this error code can also show up if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, induced by blocked airflow, can lead to this error code. Lastly, you might see error code 40 if there’s something wrong 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 turn the thermostat off and on again and error code 40 reappears, it’s best to get a hold of an experienced technician.

Honeywell Error Code e43

If the Honeywell thermostat displays error code e43, it can’t communicate with the router, and by extension the 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

Restart the router by unplugging it and leaving it that way for around 30 seconds. The thermostat might also be disconnected if you have 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 determine the temperature outdoors and indoors. If a sensor fails, you could notice error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A qualified technician can replace the sensor and reset the thermostat, which should resolve error code e1.

Honeywell Error Code 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 malfunctioning and unable to maintain a connection to the thermostat. This sometimes happens when the wiring is defective or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can employ a voltmeter to determine if there’s a poor electrical connection. In situations where the wiring on your specific HVAC system is bad, the technician can replace it. When the thermostat itself is the issue, it should probably be replaced.

Error Code e2 for Honeywell Thermostats

If you see error code e2 show up on your Honeywell smart thermostat, it can mean a few different things. In some cases, one of the sensors that detects the temperature isn’t operating properly. Other times, it means the router was disconnected from the outlet before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code stems from sensor failure, a technician should troubleshoot and swap out the impacted sensor. Any time the problem comes from disconnected power, all you have to do is verify the router stays on over the course of the setup process.