Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is an easy way to fine-tune how you use your HVAC system. But like any mechanical system, you could occasionally run into a problem. With its digital display, Honeywell smart thermostats can show an error code that certified technicians will use to get a better sense of what's happening. Here are several of the most known error codes you may see on your Honeywell smart thermostat.

Error Code e42 for Honeywell Thermostats

You may encounter this error code when your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect to. This can occur if the router fails to perform the Dynamic Host Configuration Protocol, or DHCP. This process automatically supplies the needed IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by making sure that your router is enabled for DHCP. Assuming it does, you may also have to power cycle the router and perform the setup process again with your thermostat. Doing so should see to it that the DHCP is delivered and connects to the smart thermostat.

Honeywell Error Code e02

Error code e02 appears when the password for accessing 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 need to do to solve error e02 is verify you’re putting in the correct Wi-Fi password when configuring the thermostat.

Honeywell Error Code 40

Error code 40 can pop up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most often, this appears if the compressor isn’t working despite being instructed to. But this error code can also show up if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, induced by poor airflow, can display this error code. Lastly, 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 regular operation. If you reset the thermostat and error code 40 reappears, it’s best to get a hold of an experienced technician.

Honeywell Error Code e43

If a Honeywell thermostat displays error code e43, it can’t communicate with the router, and by extension your Wi-Fi. This may 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 switched the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Thermostat Error e1

Thermostats employ sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you could 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 restart the thermostat, which should take care of 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 may 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 has failed.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can use a voltmeter to find out if there’s a poor electrical connection. If the wiring on your type of HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the issue, it will likely have to be replaced.

Honeywell Error Code e2

If you see error code e2 show up on your Honeywell smart thermostat, it could mean a few different things. In some cases, one of the sensors responsible for detecting the temperature isn’t operating like it should. In other instances, it means the router was disconnected from power 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 will troubleshoot and swap out the impacted sensor. Any time the problem stems from disconnected power, all you’ll have to do is see to it that the router remains on throughout the setup process.