Solved: Honeywell Thermostat Error Codes

November 08, 2022

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

Honeywell Thermostat Error e42

You can see 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 occur if your router does not execute the Dynamic Host Configuration Protocol, or DHCP. This procedure 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 making sure that your router is enabled for DHCP. Assuming it does, you might also need to power cycle the router and complete the initial setup process again with your thermostat. Doing so should ensure the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed if the password for accessing your home’s Wi-Fi router is incorrect. Once this error code appears 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 verify you’re putting in the correct Wi-Fi password when configuring the thermostat.

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is notified that a heat pump or air conditioner’s monitoring system has recognized a malfunction. For the most part, this occurs once the compressor isn’t working despite being directed to. But this error code could also appear if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, triggered by blocked airflow, can display this error code. And finally, you may see 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 examine the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for normal operation. If you restart the thermostat and error code 40 reappears, it’s best to contact an experienced technician.

Honeywell Thermostat Error e43

If a Honeywell thermostat shows error code e43, it can’t 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 a short period. The thermostat might also be disconnected if you have recently changed the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Thermostat Error e1

Thermostats employ sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you may see 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 take care of error code e1.

Honeywell Thermostat Error 11n

Error code 11n may appear in situations where the thermostat can’t 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 is faulty.

How to Fix Honeywell Thermostat Error 11n

A professional technician can use a voltmeter to find out if there’s a faulty electrical connection. If the wiring on your existing HVAC equipment is bad, the technician can replace it. When the thermostat itself is the issue, 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 might mean several different things. For example, one of the sensors responsible for detecting the temperature isn’t functioning like it should. Other times, it means the router was disconnected from the outlet before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is a result of sensor failure, a technician can troubleshoot and switch out the affected sensor. When the problem originates from disconnected power, all you have to do is make sure the router remains on throughout the setup process.