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 may sometimes run into a problem. With the digital display, Honeywell smart thermostats can show an error code that certified technicians can use to get a better sense of what's wrong. Here are several of the most likely error codes you may 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 hook up to. This can occur if a router does not complete the Dynamic Host Configuration Protocol, or DHCP. This process automatically sends out the necessary IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router is enabled for DHCP. If it does, you may also have to power cycle the router and complete the initial setup process again with the thermostat. Doing so should ensure the DHCP is sent and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs when the password for communicating with your home’s Wi-Fi router is incorrect. After this error code appears for 30 seconds, the thermostat’s digital display should automatically transition 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 resolve error e02 is ensure you’re entering the correct Wi-Fi password when setting up 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 identified a malfunction. Most commonly, this occurs when the compressor isn’t running despite being instructed to. But this error code can also show up if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, induced by obstructed airflow, can lead to this error code. And finally, you may experience 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 reset the thermostat and error code 40 reappears, it's time to get in touch with an experienced technician.

Honeywell Thermostat Error e43

If the Honeywell thermostat displays error code e43, it is unable to communicate with the router, and by extension the Wi-Fi. This could 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

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

Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n could appear in situations where the thermostat is unable to detect a heating or cooling unit. This may 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 has failed.

How to Fix Honeywell Thermostat Error 11n

A professional technician can use a voltmeter to determine if there’s a poor electrical connection. When the wiring on your existing HVAC equipment is bad, the technician can replace it. When the thermostat itself is the source of the error code, 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 might mean a few different things. For example, one of the sensors used to detect the temperature isn’t operating correctly. In other instances, it means the router was disconnected from the outlet before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code stems from sensor failure, a technician should troubleshoot and swap out the impacted sensor. When the problem stems from disconnected power, all you’ll have to do is see to it that the router remains on throughout the setup process.