Solved! Error Code E42 for Honeywell Smart Thermostats

A Honeywell smart thermostat is an easy way to better manage how you use your HVAC system. But like any mechanical system, you could sometimes run across a problem. With its digital display, Honeywell smart thermostats can provide an error code that trained technicians will use to get a better sense of what's going on. Here are a few of the most likely error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You might encounter this error code in the event that your home’s Wi-Fi internet did not supply an IP address for the thermostat to connect to. This can happen if a router fails to execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the required IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by confirming that your router has enabled DHCP. Assuming it does, you usually also have to power cycle the router and perform the setup process again with the thermostat. Completing this task should see to it that the DHCP is transmitted and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears whenever the password for connecting to your home’s Wi-Fi router is incorrect. When this error code appears 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 solve error e02 is make sure you’re putting in the correct Wi-Fi password when setting up the thermostat.

Honeywell Error Code 40

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. For the most part, this happens if the compressor isn’t turning on despite being directed to. But this error code could also appear if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, triggered by blocked airflow, can lead to this error code. Lastly, you may see error code 40 if there’s something wrong with the coolant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can inspect 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 contact an experienced technician.

Error Code e43 for Honeywell Thermostats

If the Honeywell thermostat shows error code e43, it is unable to communicate with the router, and by extension your Wi-Fi. This might 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’ve recently switched the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

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

Honeywell Error Code 11n

Error code 11n could appear in situations where the thermostat is unable to detect a heating or cooling unit. This can mean that the equipment itself is defective and unable to maintain a connection to the thermostat. This sometimes happens when the wiring is bad or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can utilize a voltmeter to assess if there’s a faulty electrical connection. When the wiring on your existing HVAC system is bad, the technician can replace it. When the thermostat itself is the problem, it should probably be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it could mean a couple of different things. In some cases, one of the sensors used to detect the temperature isn’t functioning correctly. In other instances, it means the router was disconnected from power before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

If 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 throughout the setup process.