Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is a great way to optimize how you use your home comfort system. But like any utility, you may sometimes run across a problem. With the digital display, Honeywell smart thermostats can display an error code that certified technicians will use to understand what's happening. Here are some of the most likely error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might encounter this error code in the event that your home’s Wi-Fi connection did not supply an IP address for the thermostat to connect to. This can happen if your router doesn't 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 fix error code e42 by making sure that your router is enabled for DHCP. Assuming it does, you may also need to power cycle the router and perform the setup process again with your thermostat. Doing so should ensure the DHCP is transmitted and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs whenever the password for connecting to your home’s Wi-Fi router is not correct. Once this error code has appeared for 30 seconds, the thermostat’s digital display should automatically transition 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 clear error e02 is verify you’re typing the correct Wi-Fi password when setting up the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can show up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most commonly, this happens once the compressor isn’t running despite being directed to. But this error code can also show up if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, triggered by blocked airflow, can display this error code. And finally, you might 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 normal operation. If you restart the thermostat and error code 40 reappears, it’s best to get in touch with 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 the wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

Reset the router by unplugging it and leaving it that way for around 30 seconds. The thermostat may also be disconnected if you’ve recently updated 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 breaks down, you might see error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A trained technician can replace the sensor and reboot the thermostat, which should clear error code e1.

Error Code 11n for Honeywell Thermostats

Error code 11n can appear in situations where the thermostat is failing to connect to a heating or cooling unit. This may mean that the equipment itself is faulty 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 licensed technician can use a voltmeter to determine if there’s a faulty electrical connection. If 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 pop up on your Honeywell smart thermostat, it could mean several different things. For example, one of the sensors that detects the temperature isn’t working like it should. In other cases, it means the router was disconnected from the outlet 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 switch out the damaged sensor. Any time the problem stems from disconnected power, all you have to do is make sure the router stays on throughout the setup process.