Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an easy way to optimize how you use your HVAC system. But like any technology, you could occasionally experience a problem. With the digital display, Honeywell smart thermostats can display an error code that professional technicians 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 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 occur if the router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This process automatically transmits the needed IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by making sure that your router can complete the DHCP. When it does, you might also need to power cycle the router and repeat the initial setup process with your thermostat. Doing so should see to it that the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs whenever the password for accessing your home’s Wi-Fi router is not correct. When this error code is displayed for 30 seconds, the thermostat’s digital display should automatically transition 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 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 notified that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most often, this happens when the compressor isn’t running despite being instructed to. But this error code may also show up if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, triggered by blocked airflow, can render this error code. Lastly, you might 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 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 get in touch with 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 the wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

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

Honeywell Thermostat Error e1

Thermostats employ sensors to detect the temperature outdoors and indoors. If a sensor fails, you may see error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A skilled technician can swap out the sensor and reset the thermostat, which should clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n could appear if the thermostat is unable 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 damaged or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can employ a voltmeter to determine if there’s a faulty electrical connection. If the wiring on your specific HVAC equipment is bad, the technician can replace it. If the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you notice error code e2 pop up on your Honeywell smart thermostat, it can mean several different things. In some cases, one of the sensors used to detect the temperature isn’t working like it should. Other times, it means the router was disconnected from power before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician should troubleshoot and swap out the impacted sensor. If the problem stems from disconnected power, all you’ll have to do is verify the router remains on over the course of the setup process.