Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is an excellent way to fine-tune how you use your heating and cooling. But like any utility, you could sometimes run into a problem. With the digital display, Honeywell smart thermostats can provide an error code that professional technicians will use to understand what's going on. Here are a few of the most likely error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can receive 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 take place if your router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically supplies the necessary 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 confirming that your router can complete the DHCP. Assuming it does, you may also need to power cycle the router and complete the initial setup process again with the thermostat. This should see to it that the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs if the password for accessing your home’s Wi-Fi router was incorrect. When 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 need to do to solve error e02 is verify you’re putting in the correct Wi-Fi password when configuring the thermostat.

Honeywell Error Code 40

Error code 40 can pop up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most often, this occurs once the compressor isn’t turning on despite being directed to. But this error code could also show up if power is shut off from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, triggered by poor airflow, can render this error code. Lastly, you might 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 ordinary operation. If you restart the thermostat and error code 40 reappears, it’s best to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat presents error code e43, it is failing to 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

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

Honeywell Thermostat Error e1

Thermostats utilize sensors to identify the temperature outdoors and indoors. If a sensor breaks down, you might notice error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n may appear when the thermostat can’t detect a heating or cooling unit. This can mean that the equipment itself is faulty and unable to maintain a connection to 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 use a voltmeter to assess if there’s a bad electrical connection. In situations where the wiring on your specific HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the problem, it should probably be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 appear on your Honeywell smart thermostat, it might mean several different things. In some cases, one of the sensors used to detect the temperature isn’t operating like it should. 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

If the error code is a result of sensor failure, a technician can troubleshoot and swap out the affected sensor. If the problem stems from disconnected power, all you'll need to do is make sure the router stays on over the course of the setup process.