Solved! Error Code E42 for Honeywell Smart Thermostats

A Honeywell smart thermostat is an excellent way to better manage how you use your HVAC system. But like any technology, you could sometimes run across a problem. With a digital display, Honeywell smart thermostats can show an error code that professional technicians can use to figure out what's happening. Here are a few of the most common error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You may receive this error code when your home’s Wi-Fi internet did not supply an IP address for the thermostat to hook up to. This can occur if a router doesn't execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically supplies the needed IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by making sure that your router is enabled for DHCP. Assuming it does, you might also have to power cycle the router and repeat the initial setup process with the thermostat. This should see to it that the DHCP is transmitted and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 is displayed if the password for connecting to your home’s Wi-Fi router is 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 attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to solve error e02 is make sure you’re entering the correct Wi-Fi password when setting up the thermostat.

Honeywell Error Code 40

Error code 40 can show up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most commonly, this happens if the compressor isn’t running despite being instructed to. But this error code could 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 lead to this error code. And finally, you might see 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 inspect 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 a hold of an experienced technician.

Honeywell Error Code e43

If your Honeywell thermostat displays error code e43, it is failing to communicate with the router, and by extension the 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

Reboot the router by unplugging it and leaving it that way for a short period. The thermostat could 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 use sensors to detect the temperature outdoors and indoors. If a sensor fails, you may notice 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 resolve 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 can mean that the equipment itself is faulty and unable to communicate with the thermostat. This sometimes happens when the wiring is damaged or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A professional technician can utilize a voltmeter to find out if there’s a bad electrical connection. If the wiring on your existing 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.

Honeywell Error Code e2

If you see error code e2 pop up on your Honeywell smart thermostat, it might mean a couple of different things. Sometimes, one of the sensors responsible for detecting the temperature isn’t functioning correctly. In other instances, it means the router was disconnected from the outlet before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is a result of sensor failure, a technician will troubleshoot and replace the damaged sensor. When the problem comes from disconnected power, all you'll need to do is make sure the router remains on throughout the setup process.