Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an easy way to fine-tune how you use your heating and cooling. But like any technology, you may occasionally run into a problem. With the digital display, Honeywell smart thermostats can display an error code that trained technicians can use to understand what's going on. Here are some of the most common error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can see this error code if your home’s Wi-Fi internet did not supply an IP address for the thermostat to connect with. This can occur if a router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by confirming that your router can complete the DHCP. If it does, you might also have to power cycle the router and repeat the initial setup process with your thermostat. This should see to it that the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed when the password for communicating with your home’s Wi-Fi router is not correct. When this error code appears for 30 seconds, the thermostat’s digital display will automatically progress 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 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 show up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most commonly, this appears if the compressor isn’t running despite being instructed to. But this error code could also surface if power is shut off from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, triggered by poor airflow, can display this error code. Lastly, you could 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 check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for normal operation. If you turn the thermostat off and on again and error code 40 reappears, it’s best to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If a Honeywell thermostat displays error code e43, it is unable 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

Reboot the router by unplugging it and leaving it that way for around 30 seconds. The thermostat might 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 fails, you may see error code e1 show up 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 clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n may appear if the thermostat is unable to recognize a heating or cooling unit. This may mean that the equipment itself is defective and unable to connect with the thermostat. This sometimes happens when the wiring is defective or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can employ a voltmeter to determine if there’s a bad electrical connection. When the wiring on your existing HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the source of the error code, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you see error code e2 appear on your Honeywell smart thermostat, it could mean a couple of different things. In some cases, one of the sensors that detects the temperature isn’t operating like it should. Other times, it means the router was disconnected from its power source before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is caused by sensor failure, a technician will troubleshoot and replace the impacted sensor. If the problem comes from disconnected power, all you’ll have to do is see to it that the router stays on over the course of the setup process.