A Honeywell smart thermostat is an excellent way to better manage how you use your home comfort system. But like any technology, you could sometimes experience a problem. With a digital display, Honeywell smart thermostats can display an error code that professional technicians can use to get a better sense of what's happening. Here are several of the most known error codes you might see on your Honeywell smart thermostat.

Honeywell Error Code e42

You may encounter this error code in the event that your home’s Wi-Fi connection did not supply an IP address for the thermostat to connect with. This can happen if your router doesn't execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically supplies the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by verifying that your router can complete the DHCP. When it does, you usually also have to power cycle the router and perform the setup process again with your thermostat. This should see to it that the DHCP is transmitted and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 occurs whenever the password for connecting to your home’s Wi-Fi router is incorrect. Once this error code is displayed for 30 seconds, the thermostat’s digital display automatically transitions 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 solve error e02 is ensure you’re entering the correct Wi-Fi password when setting up the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can show up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has identified a malfunction. For the most part, this happens once the compressor isn’t turning on despite being directed to. But this error code could also show up if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, triggered by poor airflow, can lead to this error code. Finally, you may experience 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 inspect 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 time to contact an experienced technician.

Error Code e43 for Honeywell Thermostats

If the Honeywell thermostat shows error code e43, it is failing to communicate with the router, and by extension your 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 a short period. The thermostat could also be disconnected if you have 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 malfunctions, you may notice error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A qualified technician can swap out the sensor and reset the thermostat, which should take care of error code e1.

Honeywell Error Code 11n

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

How to Fix Honeywell Thermostat Error 11n

A qualified technician can use a voltmeter to assess if there’s a faulty electrical connection. When the wiring on your type of HVAC system is bad, the technician can replace it. When the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it can mean a few different things. For example, one of the sensors that detects the temperature isn’t functioning properly. Other times, 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 caused by sensor failure, a technician will troubleshoot and replace the affected sensor. Any time the problem stems from disconnected power, all you’ll have to do is see to it that the router remains on during the setup process.