A Honeywell smart thermostat is a great way to optimize how you use your home comfort system. But like any technology, you might sometimes experience a problem. With the digital display, Honeywell smart thermostats can show an error code that trained technicians will use to figure out what's wrong. Here are a few of the most known error codes you may see on your Honeywell smart thermostat.

Honeywell Error Code e42

You might encounter this error code in the event that your home’s Wi-Fi internet did not present an IP address for the thermostat to connect to. This can occur if a router does not 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 is enabled for DHCP. Assuming it does, you may also need to power cycle the router and perform the setup process again with your thermostat. Completing this task should see to it that the DHCP is delivered and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 appears if the password for communicating with your home’s Wi-Fi router is not correct. Once 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 to enter the password again.

How to Fix Honeywell Thermostat Error e02

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

Honeywell Error Code 40

Error code 40 can pop up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has recognized a malfunction. For the most part, this appears once the compressor isn’t running despite being instructed to. But this error code may also surface if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, caused by obstructed airflow, can lead to this error code. Lastly, you might experience error code 40 if there’s something wrong 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 time to get a hold of an experienced technician.

Honeywell Error Code e43

If a Honeywell thermostat displays error code e43, it can’t communicate with the router, and by extension the 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

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

Honeywell Error Code e1

Thermostats use sensors to identify the temperature outdoors and indoors. If a sensor breaks down, you could see error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A trained technician can change out the sensor and reboot the thermostat, which should take care of error code e1.

Honeywell Thermostat Error 11n

Error code 11n could appear in situations where the thermostat is unable to detect 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 bad or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can employ a voltmeter to assess if there’s a bad 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’ve noticed error code e2 appear on your Honeywell smart thermostat, it can mean a couple of different things. Sometimes, one of the sensors used to detect the temperature isn’t operating like it should. 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 stems from sensor failure, a technician will troubleshoot and swap out the impacted sensor. When the problem stems from disconnected power, all you'll need to do is see to it that the router remains on during the setup process.