Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is a great way to optimize how you use your HVAC system. But like any mechanical system, you might occasionally run into a problem. With the digital display, Honeywell smart thermostats can provide an error code that certified technicians will use to understand what's going on. Here are a few of the most common error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You might see this error code if your home’s Wi-Fi internet did not provide an IP address for the thermostat to connect with. This can happen if your router doesn't execute the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically sends out the necessary IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by verifying that your router has enabled DHCP. When it does, you may also have to power cycle the router and complete the initial setup process again with your thermostat. Completing this task should see to it that the DHCP is delivered and connects to the smart thermostat.

Error Code e02 for Honeywell Thermostats

Error code e02 appears whenever the password for communicating with your home’s Wi-Fi router is not correct. When 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 to enter the password again.

How to Fix Honeywell Thermostat Error e02

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

Error Code 40 for Honeywell Thermostats

Error code 40 can pop up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most often, this occurs once the compressor isn’t turning on despite being directed to. But this error code can also show up if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, caused by obstructed airflow, can render this error code. Finally, you could experience error code 40 if there’s a problem with the coolant, the outdoor unit’s fan motor or the motor’s starting capacitor.

How to Fix Honeywell Thermostat Error 40

You can check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for ordinary operation. If you reset the thermostat and error code 40 reappears, you should try to get in touch with an experienced technician.

Honeywell Error Code e43

If your Honeywell thermostat shows error code e43, it is unable to communicate with the router, and by extension your 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 a short period. The thermostat may also be disconnected if you recently updated the password or the Wi-Fi’s SSID, which is the name you give it.

Error Code e1 for Honeywell Thermostats

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

How to Fix Honeywell Thermostat Error e1

A skilled technician can swap out the sensor and restart the thermostat, which should take care of error code e1.

Honeywell Error Code 11n

Error code 11n can appear in situations where the thermostat is failing to detect a heating or cooling unit. This might mean that the equipment itself is defective and unable to communicate with the thermostat. This can happen when the wiring is defective or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can use a voltmeter to assess if there’s a poor electrical connection. In situations where the wiring on your existing HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the source of the error code, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you notice 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 functioning properly. In other instances, it means the router was disconnected from the outlet before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician will troubleshoot and switch out the damaged sensor. If the problem stems from disconnected power, all you’ll have to do is make sure the router stays on throughout the setup process.