Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is an easy way to optimize how you use your HVAC system. But like any technology, you may sometimes run across a problem. With a digital display, Honeywell smart thermostats can provide an error code that professional technicians can use to get a better sense of what's going on. Here are several of the most likely error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can encounter this error code if your home’s Wi-Fi connection did not present an IP address for the thermostat to connect to. This can take place if the router fails to perform the Dynamic Host Configuration Protocol, or DHCP. This function automatically supplies the needed IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

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

Honeywell Thermostat Error e02

Error code e02 appears whenever the password for accessing your home’s Wi-Fi router was incorrect. After this error code appears for 30 seconds, the thermostat’s digital display should automatically transition 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 make sure you’re typing the correct Wi-Fi password when configuring the thermostat.

Honeywell Error Code 40

Error code 40 can pop up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most commonly, this happens if the compressor isn’t working despite being instructed to. But this error code may also show up if power is shut off from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, induced by blocked airflow, can lead to this error code. Finally, you may experience error code 40 if there’s something wrong with the coolant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can inspect 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 in touch with an experienced technician.

Error Code e43 for Honeywell Thermostats

If the Honeywell thermostat presents error code e43, it is failing to communicate with the router, and by extension your Wi-Fi. This may 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 could 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 employ sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you might notice error code e1 show up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Error Code 11n for Honeywell Thermostats

Error code 11n can appear if the thermostat is unable to detect a heating or cooling unit. This might mean that the equipment itself is faulty and unable to maintain a connection to the thermostat. This can happen when the wiring is defective or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can employ a voltmeter to find out if there’s a faulty electrical connection. In situations where the wiring on your type of HVAC equipment is bad, the technician can replace it. If the thermostat itself is the source of the error code, it will likely have to be replaced.

Honeywell Error Code e2

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it can mean a couple of different things. For example, one of the sensors used to detect the temperature isn’t operating like it should. Other times, it means the router was disconnected from power before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is caused by sensor failure, a technician can troubleshoot and swap out the affected sensor. When the problem stems from disconnected power, all you'll need to do is verify the router remains on throughout the setup process.