Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an excellent way to optimize how you use your home comfort system. But like any technology, you may occasionally experience a problem. With a digital display, Honeywell smart thermostats can provide an error code that professional technicians can use to get a better sense of what's wrong. Here are some of the most common error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can receive this error code in the event that your home’s Wi-Fi internet did not provide an IP address for the thermostat to hook up to. This can occur if a router does not execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the required IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can resolve 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 complete the initial setup process again with the thermostat. Doing so should ensure the DHCP is delivered and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs whenever the password for connecting to your home’s Wi-Fi router was incorrect. Once 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 try to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to resolve error e02 is verify you’re typing 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 recognized a malfunction. Most commonly, this occurs when the compressor isn’t turning on despite being directed to. But this error code may also appear if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, triggered by poor airflow, can display this error code. And finally, you may encounter 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 inspect 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, it’s best to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat displays error code e43, it is unable to 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 your wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

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

Honeywell Thermostat Error e1

Thermostats employ sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you may see error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A qualified technician can replace the sensor and restart the thermostat, which should take care of error code e1.

Honeywell Thermostat Error 11n

Error code 11n may appear if the thermostat can’t recognize a heating or cooling unit. This can mean that the equipment itself is faulty and unable to connect with the thermostat. This sometimes happens when the wiring is damaged 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. If the wiring on your specific HVAC system is bad, the technician can replace it. When the thermostat itself is the problem, 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 several different things. In some cases, one of the sensors responsible for detecting the temperature isn’t operating properly. In other cases, 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 caused by sensor failure, a technician will troubleshoot and replace the impacted sensor. If the problem originates from disconnected power, all you have to do is see to it that the router stays on over the course of the setup process.