Solved! Error Code E42 for Honeywell Smart Thermostats

A Honeywell smart thermostat is an easy way to better manage how you use your home comfort system. But like any technology, you could sometimes run across a problem. With the digital display, Honeywell smart thermostats can show an error code that trained technicians can use to understand what's happening. Here are some of the most common error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can encounter this error code in the event that your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect with. This can take place if the router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the required IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by verifying that your router can complete the DHCP. When it does, you usually also have to power cycle the router and perform the setup process again with the thermostat. Completing this task should ensure the DHCP is sent and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 appears if the password for accessing your home’s Wi-Fi router is not correct. When this error code is displayed 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 resolve error e02 is ensure you’re putting in the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

Error code 40 can pop up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has recognized a malfunction. For the most part, this appears when the compressor isn’t turning on despite being instructed to. But this error code may also show up if power is shut off 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 might experience error code 40 if there’s an issue with the coolant, 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 restart the thermostat and error code 40 reappears, it's time to contact an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat shows error code e43, it is unable 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 about 30 seconds. The thermostat might also be disconnected if you have recently switched the password or the Wi-Fi’s SSID, which is the name you provide it.

Error Code e1 for Honeywell Thermostats

Thermostats utilize sensors to identify the temperature outdoors and indoors. If a sensor breaks down, you may notice error code e1 show 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 clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n could appear in situations where the thermostat is failing to recognize a heating or cooling unit. This can mean that the equipment itself is malfunctioning and unable to maintain a connection to the thermostat. This can happen when the wiring is defective or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can utilize a voltmeter to assess if there’s a poor 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 issue, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you see error code e2 pop up on your Honeywell smart thermostat, it might mean a few different things. For example, one of the sensors that detects the temperature isn’t operating properly. In other instances, it means the router was disconnected from power before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code stems from sensor failure, a technician can troubleshoot and switch out the affected sensor. If the problem originates from disconnected power, all you have to do is see to it that the router stays on during the setup process.