Solved! Error Code E42 for Honeywell Smart Thermostats

A Honeywell smart thermostat is a great way to optimize how you use your HVAC system. But like any mechanical system, you may sometimes run across a problem. With the digital display, Honeywell smart thermostats can show an error code that professional technicians can use to get a better sense of what's happening. Here are some of the most known error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You might see this error code when your home’s Wi-Fi internet did not provide an IP address for the thermostat to hook up to. This can take place if the router fails to execute the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the required IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by making sure that your router has enabled DHCP. If it does, you might also need to power cycle the router and perform the setup process again with your thermostat. Completing this task should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Error Code e02

Error code e02 appears whenever the password for accessing your home’s Wi-Fi router was incorrect. Once this error code has appeared 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'll need to do to resolve error e02 is make sure you’re entering the correct Wi-Fi password when configuring the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can appear when the thermostat is notified that a heat pump or air conditioner’s monitoring system has detected a malfunction. For the most part, this happens 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 an extended period of time. A “High Pressure Fault” error, triggered by blocked airflow, can lead to this error code. Lastly, you could see error code 40 if there’s something wrong 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 time to get in touch with an experienced technician.

Honeywell Error Code e43

If your Honeywell thermostat presents error code e43, it can’t 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

Reset the router by unplugging it and leaving it that way for a short period. The thermostat could also be disconnected if you’ve recently updated the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

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

Honeywell Error Code 11n

Error code 11n may appear when the thermostat is unable to detect a heating or cooling unit. This may mean that the equipment itself is defective and unable to maintain a connection to the thermostat. This can happen 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 determine if there’s a bad electrical connection. If the wiring on your type of HVAC equipment is bad, the technician can replace it. In situations where the thermostat itself is the source of the error code, it will likely have to be replaced.

Error Code e2 for Honeywell Thermostats

If you’ve noticed error code e2 appear on your Honeywell smart thermostat, it might mean a couple of different things. For example, one of the sensors responsible for detecting the temperature isn’t operating like it should. Other times, it means the router was disconnected from its power source before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code stems from sensor failure, a technician should troubleshoot and swap out the impacted sensor. If the problem stems from disconnected power, all you’ll have to do is verify the router stays on throughout the setup process.