A Honeywell smart thermostat is an excellent way to better manage how you use your home comfort system. But like any mechanical system, you might occasionally run into a problem. With its digital display, Honeywell smart thermostats can provide an error code that certified technicians can use to understand what's happening. Here are several of the most likely error codes you might see on your Honeywell smart thermostat.

Error Code e42 for Honeywell Thermostats

You may receive this error code in the event that your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect with. This can take place if your router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This function automatically sends out the needed IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by verifying that your router can complete the DHCP. If it does, you may also have to power cycle the router and repeat the initial setup process with your thermostat. Doing so should see to it that the DHCP is transmitted and connects to your smart thermostat.

Honeywell Error Code e02

Error code e02 is displayed when the password for connecting to your home’s Wi-Fi router was incorrect. When this error code has appeared for 30 seconds, the thermostat’s digital display automatically transitions 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 entering the correct Wi-Fi password when setting up the thermostat.

Honeywell Error Code 40

Error code 40 can appear when the thermostat is informed that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most commonly, this appears when the compressor isn’t turning on despite being instructed to. But this error code can also show up if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, caused by blocked airflow, can lead to this error code. Lastly, 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 check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for ordinary operation. If you restart the thermostat and error code 40 reappears, it’s best to get a hold of an experienced technician.

Honeywell Error Code e43

If a Honeywell thermostat shows error code e43, it is failing to communicate with the router, and by extension your Wi-Fi. This could 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

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

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

A trained technician can change out the sensor and reset the thermostat, which should clear error code e1.

Honeywell Error Code 11n

Error code 11n can appear if the thermostat can’t recognize a heating or cooling unit. This may mean that the equipment itself is faulty and unable to maintain a connection to the thermostat. This sometimes happens 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 find out if there’s a bad electrical connection. In situations where the wiring on your specific HVAC system is bad, the technician can replace it. If 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 a few different things. For example, one of the sensors that detects the temperature isn’t functioning correctly. In other cases, it means the router was disconnected from the outlet before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is caused by sensor failure, a technician will troubleshoot and switch out the affected sensor. Any time the problem stems from disconnected power, all you’ll have to do is see to it that the router remains on over the course of the setup process.