Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is a great way to fine-tune how you use your heating and cooling. But like any mechanical system, you could occasionally experience a problem. With a digital display, Honeywell smart thermostats can show an error code that certified technicians can use to figure out what's wrong. Here are several of the most known error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You may receive this error code if your home’s Wi-Fi connection did not present an IP address for the thermostat to connect to. This can take place if a router fails to execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically transmits the required IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

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

Honeywell Error Code e02

Error code e02 occurs if the password for accessing your home’s Wi-Fi router is incorrect. After this error code appears for 30 seconds, the thermostat’s digital display should automatically transition to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you need to do to resolve 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 show up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most commonly, this appears when the compressor isn’t turning on despite being directed to. But this error code could also surface if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, induced by blocked airflow, can render this error code. And finally, you might encounter 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 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, it's time to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat presents error code e43, it is failing 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 your wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

Restart the router by unplugging it and leaving it that way for about 30 seconds. The thermostat may also be disconnected if you recently updated the password or the Wi-Fi’s SSID, which is the name you provide it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

A skilled technician can change out the sensor and reset the thermostat, which should resolve error code e1.

Honeywell Thermostat Error 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 maintain a connection to the thermostat. This can happen when the wiring is damaged or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can utilize a voltmeter to assess if there’s a faulty electrical connection. If the wiring on your specific HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the issue, it should probably be replaced.

Honeywell Error Code e2

If you notice error code e2 appear on your Honeywell smart thermostat, it can mean a few different things. For example, one of the sensors used to detect the temperature isn’t functioning correctly. 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 is a result of sensor failure, a technician should troubleshoot and switch out the damaged sensor. If the problem originates from disconnected power, all you'll need to do is see to it that the router stays on over the course of the setup process.