Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is an excellent way to optimize how you use your HVAC system. But like any technology, you might occasionally experience a problem. With its digital display, Honeywell smart thermostats can display an error code that trained technicians can use to understand what's wrong. Here are some of the most likely error codes you might see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can encounter this error code when your home’s Wi-Fi internet did not supply an IP address for the thermostat to connect with. This can happen if your router does not perform the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the required IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router is enabled for DHCP. When it does, you might also have to power cycle the router and perform the setup process again with the thermostat. Doing so should ensure the DHCP is transmitted 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 was incorrect. Once this error code is displayed for 30 seconds, the thermostat’s digital display automatically transitions to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

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

Honeywell Error Code 40

Error code 40 can appear when the thermostat is notified that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most often, this occurs once the compressor isn’t running despite being instructed to. But this error code can 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 display this error code. Finally, you could 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 regular operation. If you restart the thermostat and error code 40 reappears, it's time to get a hold of an experienced technician.

Honeywell Error Code e43

If a Honeywell thermostat shows error code e43, it can’t communicate with the router, and by extension the Wi-Fi. This may 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 might also be disconnected if you recently changed the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

A skilled technician can swap out the sensor and restart the thermostat, which should resolve error code e1.

Honeywell Thermostat Error 11n

Error code 11n could appear when the thermostat can’t recognize a heating or cooling unit. This may mean that the equipment itself is malfunctioning and unable to communicate with the thermostat. This sometimes happens when the wiring is damaged or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can utilize a voltmeter to find out if there’s a faulty electrical connection. In situations where the wiring on your type of HVAC system is bad, the technician can replace it. If the thermostat itself is the issue, it should probably be replaced.

Honeywell Error Code e2

If you notice error code e2 show up on your Honeywell smart thermostat, it can mean a couple of different things. Sometimes, one of the sensors used to detect the temperature isn’t functioning correctly. Other times, it means the router was disconnected from power before the thermostat finished 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 damaged sensor. If the problem comes from disconnected power, all you'll need to do is make sure the router remains on over the course of the setup process.