Solved: Honeywell Thermostat Error Codes

November 08, 2022

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

Honeywell Thermostat Error e42

You might receive this error code if your home’s Wi-Fi connection did not present an IP address for the thermostat to connect to. This can take place if your router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This procedure 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 verifying that your router is enabled for DHCP. When it does, you usually also need to power cycle the router and complete the initial setup process again with your thermostat. This should ensure the DHCP is delivered and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed if the password for connecting to your home’s Wi-Fi router was incorrect. When this error code is displayed for 30 seconds, the thermostat’s digital display will automatically progress to the Wi-Fi setup screen so you can try to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you need to do to resolve error e02 is ensure you’re typing the correct Wi-Fi password when configuring the thermostat.

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most often, this happens if the compressor isn’t working despite being directed to. But this error code may also surface if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, triggered by poor airflow, can lead to this error code. Finally, you might encounter error code 40 if there’s a problem with the refrigerant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can inspect the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for regular operation. If you turn the thermostat off and on again and error code 40 reappears, it's time to get in touch with an experienced technician.

Honeywell Thermostat Error e43

If the Honeywell thermostat presents error code e43, it is unable to communicate with the router, and by extension the Wi-Fi. This might 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 about 30 seconds. The thermostat might also be disconnected if you’ve recently changed the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

A trained technician can replace the sensor and reset 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 can mean that the equipment itself is defective and unable to communicate with the thermostat. This sometimes happens when the wiring is bad or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A professional technician can utilize a voltmeter to determine if there’s a poor electrical connection. If the wiring on your existing 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 appear on your Honeywell smart thermostat, it might mean several different things. For example, one of the sensors that detects the temperature isn’t functioning 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

In situations where the error code is a result of sensor failure, a technician will troubleshoot and replace the impacted sensor. When the problem originates from disconnected power, all you have to do is verify the router remains on over the course of the setup process.