Solved! Error Code E42 for Honeywell Smart Thermostats

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

Honeywell Error Code e42

You can receive this error code when your home’s Wi-Fi internet did not provide an IP address for the thermostat to connect to. This can take place if your router doesn't execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically transmits the required IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by making sure that your router can complete the DHCP. When it does, you usually also need to power cycle the router and perform the setup process again with your thermostat. Doing so should ensure the DHCP is sent and connects to your smart thermostat.

Honeywell Error Code e02

Error code e02 appears whenever the password for connecting to your home’s Wi-Fi router was incorrect. When 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 need to do to solve error e02 is ensure you’re typing the correct Wi-Fi password when configuring the thermostat.

Honeywell Error Code 40

Error code 40 can show up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most commonly, this appears if the compressor isn’t working despite being directed to. But this error code could also surface if power is shut off from the outdoor unit for a long period of time. A “High Pressure Fault” error, triggered by poor airflow, can display this error code. And finally, you could encounter error code 40 if there’s a problem 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 restart the thermostat and error code 40 reappears, it’s best to contact an experienced technician.

Error Code e43 for Honeywell Thermostats

If the 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

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

Error Code e1 for Honeywell Thermostats

Thermostats use sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you could notice 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 reboot the thermostat, which should resolve error code e1.

Error Code 11n for Honeywell Thermostats

Error code 11n can appear in situations where the thermostat can’t recognize 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 qualified technician can use a voltmeter to find out if there’s a poor electrical connection. When the wiring on your existing HVAC equipment is bad, the technician can replace it. If the thermostat itself is the issue, it should probably be replaced.

Error Code e2 for Honeywell Thermostats

If you notice error code e2 show up on your Honeywell smart thermostat, it can mean several different things. Sometimes, one of the sensors that detects the temperature isn’t working properly. Other times, it means the router was disconnected from power before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code stems from sensor failure, a technician can troubleshoot and switch out the impacted sensor. When the problem comes from disconnected power, all you have to do is verify the router stays on over the course of the setup process.