Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is a great way to optimize how you use your heating and cooling. But like any utility, you might sometimes run into a problem. With the digital display, Honeywell smart thermostats can provide an error code that certified technicians use to figure out what's going on. Here are some of the most known error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You may encounter this error code if your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect to. This can happen if a router does not execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the needed IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by making sure that your router can complete the DHCP. If it does, you may also have to power cycle the router and perform the setup process again with your thermostat. Completing this task should ensure the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears if the password for accessing your home’s Wi-Fi router was incorrect. Once this error code appears for 30 seconds, the thermostat’s digital display should automatically transition to the Wi-Fi setup screen so you can try the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to resolve error e02 is ensure you’re typing the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is notified that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most commonly, this appears if the compressor isn’t turning on despite being instructed to. But this error code may also show up if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, caused by obstructed airflow, can display this error code. Finally, you may experience error code 40 if there’s a problem 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 normal operation. If you restart the thermostat and error code 40 reappears, you should try to get in touch with an experienced technician.

Honeywell Error Code e43

If your Honeywell thermostat displays error code e43, it is unable to communicate with the router, and by extension the 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

Reboot the router by unplugging it and leaving it that way for a short period. The thermostat might also be disconnected if you have recently changed the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

A skilled technician can swap out the sensor and reset the thermostat, which should take care of error code e1.

Honeywell Error Code 11n

Error code 11n may appear when the thermostat is failing to recognize a heating or cooling unit. This might mean that the equipment itself is faulty and unable to connect with the thermostat. This can happen when the wiring is bad or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A professional technician can employ a voltmeter to assess if there’s a poor electrical connection. In situations where the wiring on your specific HVAC equipment is bad, the technician can replace it. If the thermostat itself is the issue, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you see error code e2 appear on your Honeywell smart thermostat, it could mean a few different things. Sometimes, one of the sensors that detects the temperature isn’t working properly. In other instances, it means the router was disconnected from power 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 should troubleshoot and switch out the impacted sensor. When the problem comes from disconnected power, all you’ll have to do is verify the router stays on during the setup process.