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 might sometimes experience a problem. With a digital display, Honeywell smart thermostats can show an error code that certified technicians use to figure out what's wrong. Here are several of the most likely error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might encounter this error code if your home’s Wi-Fi connection did not present an IP address for the thermostat to connect to. This can occur if your router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This function automatically transmits the required IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router can complete the DHCP. Assuming it does, you usually also need to power cycle the router and perform the setup process again with your thermostat. This should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs if the password for accessing your home’s Wi-Fi router was 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 try the password again.

How to Fix Honeywell Thermostat Error e02

All you need to do to resolve error e02 is make sure you’re entering the correct Wi-Fi password when configuring 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 recognized a malfunction. Most commonly, this happens if the compressor isn’t running despite being instructed to. But this error code could also appear if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, induced by poor airflow, can display this error code. And finally, you might encounter 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 regular operation. If you restart the thermostat and error code 40 reappears, you should try to get in touch with an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat presents error code e43, it is failing 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

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

Honeywell Thermostat Error e1

Thermostats use sensors to identify the temperature outdoors and indoors. If a sensor malfunctions, you might notice error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n can appear when the thermostat is unable to connect to a heating or cooling unit. This can mean that the equipment itself is malfunctioning 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 licensed technician can utilize a voltmeter to assess if there’s a faulty electrical connection. In situations where the wiring on your existing HVAC equipment is bad, the technician can replace it. In situations where the thermostat itself is the issue, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you see error code e2 pop up on your Honeywell smart thermostat, it might mean a couple of different things. In some cases, one of the sensors used to detect the temperature isn’t functioning correctly. In other instances, it means the router was disconnected from its power source before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician should troubleshoot and replace the impacted sensor. If the problem comes from disconnected power, all you have to do is verify the router remains on during the setup process.