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 technology, you could sometimes run into a problem. With its digital display, Honeywell smart thermostats can show an error code that trained technicians can use to figure out what's going on. Here are several of the most common error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might encounter this error code in the event that your home’s Wi-Fi internet did not supply an IP address for the thermostat to connect with. This can take place if a router fails to execute the Dynamic Host Configuration Protocol, or DHCP. This process automatically supplies the necessary IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by confirming that your router is enabled for DHCP. Assuming it does, you usually also need to power cycle the router and perform the setup process again with the thermostat. This should see to it that the DHCP is sent and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

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

How to Fix Honeywell Thermostat Error e02

All you'll need to do to solve error e02 is verify you’re putting in the correct Wi-Fi password when configuring the thermostat.

Honeywell Thermostat Error 40

Error code 40 can show up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most commonly, this happens once the compressor isn’t running despite being instructed to. But this error code may also appear if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, caused by obstructed airflow, can display this error code. And finally, you could experience error code 40 if there’s something wrong with the coolant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can examine 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, you should try to get in touch with an experienced technician.

Honeywell Thermostat Error e43

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

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

Honeywell Thermostat Error e1

Thermostats use sensors to detect the temperature outdoors and indoors. If a sensor breaks down, you may notice error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A skilled technician can replace the sensor and reboot the thermostat, which should resolve error code e1.

Honeywell Thermostat Error 11n

Error code 11n may appear when the thermostat is failing to detect a heating or cooling unit. This may mean that the equipment itself is malfunctioning and unable to communicate with the thermostat. This sometimes happens when the wiring is damaged or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can use a voltmeter to determine if there’s a poor electrical connection. If the wiring on your specific HVAC system is bad, the technician can replace it. When the thermostat itself is the problem, it will likely have to be replaced.

Error Code e2 for Honeywell Thermostats

If you see error code e2 appear on your Honeywell smart thermostat, it could mean a few different things. Sometimes, one of the sensors used to detect the temperature isn’t working properly. In other cases, it means the router was disconnected from its power source before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

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