A Honeywell smart thermostat is an easy way to better manage how you use your home comfort system. But like any utility, you could sometimes experience a problem. With the digital display, Honeywell smart thermostats can display an error code that trained technicians can use to get a better sense of what's happening. Here are a few of the most common error codes you might see on your Honeywell smart thermostat.

Honeywell Error Code e42

You might receive this error code if your home’s Wi-Fi internet did not supply an IP address for the thermostat to connect to. This can occur if the router does not complete the Dynamic Host Configuration Protocol, or DHCP. This process automatically sends out the necessary IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by making sure that your router can complete the DHCP. If it does, you may also need to power cycle the router and repeat the initial setup process with your thermostat. This should see to it that the DHCP is transmitted and connects to your smart thermostat.

Honeywell Error Code e02

Error code e02 appears when the password for accessing your home’s Wi-Fi router is not correct. After this error code is displayed for 30 seconds, the thermostat’s digital display automatically transitions to the Wi-Fi setup screen so you can attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you have to do to resolve error e02 is ensure 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 identified a malfunction. For the most part, 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 a long period of time. A “High Pressure Fault” error, triggered by poor airflow, can display this error code. Lastly, you could see error code 40 if there’s an issue with the refrigerant, 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 normal operation. If you reset the thermostat and error code 40 reappears, it’s best to contact an experienced technician.

Honeywell Thermostat Error e43

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

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

Error Code e1 for Honeywell Thermostats

Thermostats use sensors to detect the temperature outdoors and indoors. If a sensor breaks down, you might see error code e1 show up 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.

Error Code 11n for Honeywell Thermostats

Error code 11n could appear if the thermostat can’t connect to 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 professional technician can employ a voltmeter to find out if there’s a faulty electrical connection. In situations where the wiring on your specific HVAC system is bad, the technician can replace it. When the thermostat itself is the issue, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you notice error code e2 appear on your Honeywell smart thermostat, it can mean a few different things. Sometimes, one of the sensors that detects the temperature isn’t functioning like it should. Other times, it means the router was disconnected from the outlet before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is caused by sensor failure, a technician will troubleshoot and replace the damaged sensor. If the problem comes from disconnected power, all you have to do is see to it that the router remains on during the setup process.