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 technology, you might sometimes run into a problem. With a digital display, Honeywell smart thermostats can show an error code that professional technicians use to figure out what's happening. Here are several of the most likely error codes you might see on your Honeywell smart thermostat.

Honeywell Error Code e42

You might encounter this error code when your home’s Wi-Fi connection did not provide an IP address for the thermostat to hook up to. This can occur if your router does not complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically sends out the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by verifying that your router can complete the DHCP. If it does, you usually also need to power cycle the router and repeat the initial setup process with your thermostat. This should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs whenever the password for communicating with your home’s Wi-Fi router was incorrect. 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 attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to clear 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 pop up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most commonly, this occurs if the compressor isn’t running despite being directed to. But this error code can also appear if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, caused by poor airflow, can render 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 check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for ordinary operation. If you restart the thermostat and error code 40 reappears, it’s best to get a hold of an experienced technician.

Error Code e43 for Honeywell Thermostats

If the Honeywell thermostat shows 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

Reset the router by unplugging it and leaving it that way for around 30 seconds. The thermostat could also be disconnected if you have recently changed the password or the Wi-Fi’s SSID, which is the name you create for it.

Error Code e1 for Honeywell Thermostats

Thermostats use sensors to detect the temperature outdoors and indoors. If a sensor breaks down, you could notice error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n may appear in situations where the thermostat is unable to connect to a heating or cooling unit. This might mean that the equipment itself is defective 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 employ a voltmeter to find out if there’s a poor electrical connection. When the wiring on your type of 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 show up on your Honeywell smart thermostat, it can mean a couple of different things. For example, one of the sensors responsible for detecting the temperature isn’t working properly. In other instances, it means the router was disconnected from its power source before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is a result of 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 verify the router stays on over the course of the setup process.