Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is a great way to better manage how you use your HVAC system. But like any mechanical system, you could sometimes experience a problem. With a digital display, Honeywell smart thermostats can show an error code that trained technicians can use to understand what's happening. Here are a few of the most common error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

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

How to Fix Honeywell Thermostat Error e42

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

Honeywell Error Code e02

Error code e02 appears when the password for connecting to your home’s Wi-Fi router is incorrect. When this error code appears for 30 seconds, the thermostat’s digital display should automatically transition 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 clear error e02 is verify you’re typing the correct Wi-Fi password when configuring the thermostat.

Honeywell Error Code 40

Error code 40 can appear when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most commonly, this appears if the compressor isn’t running despite being directed to. But this error code can also appear if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, triggered by poor airflow, can lead to this error code. And finally, you might see 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 ordinary operation. If you restart the thermostat and error code 40 reappears, it’s best to contact an experienced technician.

Honeywell Thermostat Error e43

If the Honeywell thermostat presents error code e43, it is unable to communicate with the router, and by extension the Wi-Fi. This can 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

Restart the router by unplugging it and leaving it that way for around 30 seconds. The thermostat could also be disconnected if you’ve recently switched the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Error Code e1

Thermostats utilize sensors to detect the temperature outdoors and indoors. If a sensor malfunctions, you could see error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n could appear in situations where the thermostat can’t detect a heating or cooling unit. This may mean that the equipment itself is defective 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 use a voltmeter to determine if there’s a poor electrical connection. If the wiring on your existing HVAC equipment is bad, the technician can replace it. When the thermostat itself is the source of the error code, it should probably be replaced.

Error Code e2 for Honeywell Thermostats

If you’ve noticed error code e2 show up on your Honeywell smart thermostat, it could mean a few different things. Sometimes, one of the sensors responsible for detecting the temperature isn’t working properly. Other times, it means the router was disconnected from its power source before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code is a result of sensor failure, a technician can troubleshoot and swap out the damaged sensor. Any time the problem comes from disconnected power, all you’ll have to do is see to it that the router stays on over the course of the setup process.