Solved! Error Code E42 for Honeywell Smart Thermostats

A Honeywell smart thermostat is a great way to fine-tune how you use your home comfort system. But like any utility, you might occasionally run into a problem. With the digital display, Honeywell smart thermostats can show an error code that professional technicians can use to figure out what's happening. Here are several of the most likely error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You may see this error code if your home’s Wi-Fi internet did not present an IP address for the thermostat to hook up to. This can occur if your router fails to perform the Dynamic Host Configuration Protocol, or DHCP. This process automatically sends out the required IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router is enabled for DHCP. When it does, you might also have to power cycle the router and perform the setup process again 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 automatically transitions to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you need to do to resolve error e02 is make sure you’re putting in 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 notified that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most often, this happens if the compressor isn’t running despite being instructed to. But this error code can also surface if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, induced by poor airflow, can render this error code. And finally, you may experience 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 ordinary operation. If you turn the thermostat off and on again and error code 40 reappears, you should try to get a hold of an experienced technician.

Error Code e43 for Honeywell Thermostats

If a Honeywell thermostat displays error code e43, it is unable to communicate with the router, and by extension the Wi-Fi. This might 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 may also be disconnected if you have recently switched the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Error Code e1

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

How to Fix Honeywell Thermostat Error e1

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

Error Code 11n for Honeywell Thermostats

Error code 11n can appear when the thermostat can’t connect to a heating or cooling unit. This can mean that the equipment itself is malfunctioning and unable to communicate with the thermostat. This sometimes happens when the wiring is bad or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A professional technician can employ a voltmeter to find out if there’s a bad electrical connection. If the wiring on your specific HVAC equipment is bad, the technician can replace it. When the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Error Code e2

If you notice error code e2 show up on your Honeywell smart thermostat, it could 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 its power source before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code stems from sensor failure, a technician will troubleshoot and replace the impacted sensor. When the problem stems from disconnected power, all you’ll have to do is see to it that the router stays on throughout the setup process.