Solved! Error Code E42 for Honeywell Smart Thermostats

A Honeywell smart thermostat is a great way to fine-tune how you use your heating and cooling. But like any technology, you may sometimes run into a problem. With the digital display, Honeywell smart thermostats can display an error code that professional technicians use to get a better sense of what's wrong. Here are several of the most likely error codes you might see on your Honeywell smart thermostat.

Honeywell Error Code e42

You may receive this error code in the event that your home’s Wi-Fi connection did not supply an IP address for the thermostat to hook up to. This can take place if a router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This process automatically transmits 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 confirming 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. Doing so should see to it that the DHCP is delivered and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 is displayed when the password for connecting to your home’s Wi-Fi router is incorrect. Once this error code appears for 30 seconds, the thermostat’s digital display will automatically progress to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you have 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 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 can also appear if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, triggered by obstructed airflow, can display this error code. Finally, you could 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 inspect the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for regular operation. If you turn the thermostat off and on again and error code 40 reappears, it’s best to get in touch with an experienced technician.

Error Code e43 for Honeywell Thermostats

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

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

Honeywell Error Code e1

Thermostats employ sensors to identify the temperature outdoors and indoors. If a sensor fails, you may see error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A qualified technician can replace the sensor and restart the thermostat, which should clear error code e1.

Error Code 11n for Honeywell Thermostats

Error code 11n could appear when the thermostat is failing 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 defective or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A professional technician can employ a voltmeter to assess if there’s a poor electrical connection. If the wiring on your type of HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the problem, it will likely have to be replaced.

Error Code e2 for Honeywell Thermostats

If you notice error code e2 appear on your Honeywell smart thermostat, it can mean several different things. For example, one of the sensors used to detect the temperature isn’t functioning properly. Other times, it means the router was disconnected from its power source before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is a result of sensor failure, a technician will troubleshoot and swap out the damaged sensor. When the problem stems from disconnected power, all you’ll have to do is make sure the router stays on during the setup process.