A Honeywell smart thermostat is an excellent way to optimize how you use your home comfort system. But like any utility, you could occasionally run across a problem. With its digital display, Honeywell smart thermostats can provide an error code that professional technicians will use to figure out what's wrong. Here are a few of the most common error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

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

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by verifying that your router can complete the DHCP. When it does, you usually also need to power cycle the router and repeat the initial setup process with the thermostat. Doing so should ensure the DHCP is transmitted and connects to the smart thermostat.

Honeywell Error Code e02

Error code e02 occurs when the password for accessing your home’s Wi-Fi router was incorrect. When this error code appears 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 have to do to resolve error e02 is make sure you’re typing the correct Wi-Fi password when configuring the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can show up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most often, this appears when the compressor isn’t turning on despite being instructed to. But this error code can also appear if power is shut off from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, induced by obstructed airflow, can render this error code. And finally, you might encounter error code 40 if there’s an issue with the coolant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for ordinary operation. If you reset the thermostat and error code 40 reappears, it’s best to get a hold of an experienced technician.

Error Code e43 for Honeywell Thermostats

If the Honeywell thermostat displays error code e43, it can’t communicate with the router, and by extension your Wi-Fi. This may 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

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

Honeywell Thermostat Error e1

Thermostats utilize sensors to identify the temperature outdoors and indoors. If a sensor malfunctions, you could notice error code e1 turn up 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 resolve error code e1.

Honeywell Thermostat Error 11n

Error code 11n could appear if the thermostat is unable to connect to a heating or cooling unit. This may mean that the equipment itself is defective and unable to maintain a connection to 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 licensed technician can use a voltmeter to find out if there’s a bad electrical connection. In situations where the wiring on your type of HVAC equipment is bad, the technician can replace it. When the thermostat itself is the problem, it will likely have to be replaced.

Error Code e2 for Honeywell Thermostats

If you see error code e2 appear on your Honeywell smart thermostat, it can mean several different things. For example, one of the sensors responsible for detecting the temperature isn’t functioning properly. In other cases, it means the router was disconnected from power before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is caused by sensor failure, a technician can troubleshoot and replace the affected sensor. When the problem stems from disconnected power, all you’ll have to do is verify the router stays on throughout the setup process.