A Honeywell smart thermostat is an excellent way to fine-tune how you use your home comfort system. But like any mechanical system, you could occasionally run into a problem. With its digital display, Honeywell smart thermostats can display an error code that professional technicians use to understand what's happening. Here are a few of the most common error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might encounter this error code when your home’s Wi-Fi internet did not provide an IP address for the thermostat to hook up to. This can happen if the router fails to perform the Dynamic Host Configuration Protocol, or DHCP. This process automatically supplies the necessary IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by verifying that your router is enabled for DHCP. If it does, you may also have to power cycle the router and perform the setup process again with your thermostat. Completing this task should see to it that the DHCP is sent and connects to your smart thermostat.

Honeywell Error Code e02

Error code e02 appears when the password for communicating with your home’s Wi-Fi router was incorrect. Once this error code has appeared 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 resolve error e02 is verify you’re putting in the correct Wi-Fi password when setting up 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 recognized a malfunction. Most often, this happens once the compressor isn’t turning on despite being directed to. But this error code could also surface if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, induced by obstructed airflow, can lead to this error code. And finally, you might encounter error code 40 if there’s an issue 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 normal operation. If you reset the thermostat and error code 40 reappears, it’s best to contact an experienced technician.

Error Code e43 for Honeywell Thermostats

If a Honeywell thermostat displays error code e43, it is failing to communicate with the router, and by extension your Wi-Fi. This might 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

Reboot the router by unplugging it and leaving it that way for around 30 seconds. The thermostat may also be disconnected if you’ve recently switched the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

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

Honeywell Error Code 11n

Error code 11n can appear when 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 defective or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can utilize a voltmeter to assess if there’s a poor electrical connection. If the wiring on your existing HVAC equipment is bad, the technician can replace it. If the thermostat itself is the issue, it should probably be replaced.

Error Code e2 for Honeywell Thermostats

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it might mean a few different things. For example, one of the sensors that detects the temperature isn’t functioning correctly. In other cases, it means the router was disconnected from its power source before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is a result of sensor failure, a technician will troubleshoot and swap out the damaged sensor. When the problem originates from disconnected power, all you have to do is see to it that the router stays on over the course of the setup process.