Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is a great way to optimize how you use your HVAC system. But like any technology, you could sometimes run across a problem. With the digital display, Honeywell smart thermostats can display an error code that trained technicians can use to figure out what's wrong. Here are a few of the most likely error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might encounter this error code in the event that your home’s Wi-Fi internet did not provide an IP address for the thermostat to connect to. This can happen if your router does not execute the Dynamic Host Configuration Protocol, or DHCP. This process automatically transmits 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 can complete the DHCP. If it does, you may also need to power cycle the router and perform the setup process again with the thermostat. This should see to it that the DHCP is sent and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed if the password for communicating with your home’s Wi-Fi router was incorrect. When this error code has appeared 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 have to do to solve error e02 is make sure you’re entering the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

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. Most often, this occurs if the compressor isn’t turning on despite being directed to. But this error code could also appear if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, triggered by obstructed airflow, can render this error code. Finally, you could see 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 ordinary operation. If you reset the thermostat and error code 40 reappears, it's time 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 the Wi-Fi. This may 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 about 30 seconds. The thermostat may also be disconnected if you have recently changed the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Thermostat Error e1

Thermostats use sensors to identify the temperature outdoors and indoors. If a sensor breaks down, you might see error code e1 show 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 clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n may appear when the thermostat is unable to detect 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 bad or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A professional technician can utilize 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 should probably be replaced.

Honeywell Thermostat Error e2

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

How to Fix Honeywell Thermostat Error e2

If the error code is caused by sensor failure, a technician can troubleshoot and replace the damaged sensor. Any time the problem comes from disconnected power, all you’ll have to do is make sure the router remains on throughout the setup process.