Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is a great way to fine-tune how you use your home comfort system. But like any utility, you may sometimes run across a problem. With a digital display, Honeywell smart thermostats can display an error code that trained technicians can use to figure out what's going on. Here are several of the most likely error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can see this error code in the event that your home’s Wi-Fi internet did not provide an IP address for the thermostat to connect to. This can happen if a router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically sends out the needed IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can resolve error code e42 by confirming that your router is enabled for DHCP. Assuming it does, you might also have to power cycle the router and perform the setup process again with the thermostat. Completing this task should ensure the DHCP is sent and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs whenever the password for connecting to your home’s Wi-Fi router was incorrect. After this error code has appeared for 30 seconds, the thermostat’s digital display should automatically transition 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 solve error e02 is make sure you’re entering the correct Wi-Fi password when configuring the thermostat.

Honeywell Thermostat Error 40

Error code 40 can pop up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most commonly, this occurs when the compressor isn’t running despite being instructed to. But this error code could also appear if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, triggered by blocked airflow, can render this error code. And finally, you may 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 examine 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 a hold of an experienced technician.

Honeywell Thermostat Error e43

If a Honeywell thermostat displays 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 your wide area network (WAN).

How to Fix Honeywell Thermostat Error e43

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

Honeywell Thermostat Error e1

Thermostats utilize sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you might notice error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n may appear in situations where the thermostat is unable to recognize 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 bad 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 poor electrical connection. If the wiring on your specific HVAC equipment is bad, the technician can replace it. In situations where the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 appear on your Honeywell smart thermostat, it could mean several different things. For example, one of the sensors responsible for detecting the temperature isn’t functioning like it should. Other times, it means the router was disconnected from power before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

When the error code stems from sensor failure, a technician can troubleshoot and replace the impacted sensor. If the problem stems from disconnected power, all you'll need to do is see to it that the router remains on during the setup process.