A Honeywell smart thermostat is an excellent way to better manage how you use your home comfort system. But like any mechanical system, you could occasionally run across a problem. With a digital display, Honeywell smart thermostats can provide an error code that professional technicians use to understand what's wrong. Here are a few of the most known error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might see this error code when your home’s Wi-Fi internet did not present an IP address for the thermostat to connect to. This can happen if a router does not complete the Dynamic Host Configuration Protocol, or DHCP. This process automatically sends out the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by making sure that your router is enabled for DHCP. Assuming it does, you might also need to power cycle the router and perform the setup process again with your thermostat. This should see to it that the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed when the password for accessing your home’s Wi-Fi router is not correct. Once this error code is displayed 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 verify you’re typing the correct Wi-Fi password when setting up 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 identified a malfunction. For the most part, this occurs when the compressor isn’t turning on despite being instructed 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 blocked airflow, can lead to this error code. Finally, you might encounter error code 40 if there’s a problem 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 turn the thermostat off and on again and error code 40 reappears, it's time to get in touch with an experienced technician.

Error Code e43 for Honeywell Thermostats

If a Honeywell thermostat displays error code e43, it is unable to communicate with the router, and by extension the Wi-Fi. This could 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 about 30 seconds. The thermostat could also be disconnected if you’ve recently changed the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

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

Error Code 11n for Honeywell Thermostats

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

How to Fix Honeywell Thermostat Error 11n

A licensed technician can use a voltmeter to assess if there’s a bad electrical connection. When the wiring on your existing HVAC system is bad, the technician can replace it. If the thermostat itself is the source of the error code, it should probably be replaced.

Error Code e2 for Honeywell Thermostats

If you see error code e2 pop up on your Honeywell smart thermostat, it could mean several different things. Sometimes, one of the sensors responsible for detecting the temperature isn’t working correctly. In other cases, it means the router was disconnected from its power source before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is a result of sensor failure, a technician can troubleshoot and replace the affected sensor. When the problem comes from disconnected power, all you’ll have to do is see to it that the router stays on during the setup process.