Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an excellent way to fine-tune how you use your home comfort system. But like any mechanical system, you may occasionally run across a problem. With a digital display, Honeywell smart thermostats can provide an error code that certified technicians can use to figure out what's happening. Here are a few of the most likely error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can encounter this error code if your home’s Wi-Fi connection did not supply an IP address for the thermostat to connect to. This can occur if a router doesn't complete the Dynamic Host Configuration Protocol, or DHCP. This function automatically supplies the required 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. Assuming it does, you usually also need to power cycle the router and perform the setup process again with your thermostat. Completing this task should ensure the DHCP is delivered and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs when the password for communicating with your home’s Wi-Fi router was incorrect. When 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 have to do to resolve error e02 is verify you’re entering the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

Error code 40 can pop up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most commonly, this appears once the compressor isn’t running despite being instructed to. But this error code may also surface if power is disconnected from the outdoor unit for a long period of time. A “High Pressure Fault” error, triggered by poor airflow, can render this error code. Lastly, you might encounter error code 40 if there’s something wrong 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 ordinary operation. If you restart the thermostat and error code 40 reappears, you should try to get in touch with an experienced technician.

Honeywell Thermostat Error e43

If a Honeywell thermostat displays error code e43, it can’t communicate with the router, and by extension your Wi-Fi. This might 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’ve recently changed the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Thermostat Error e1

Thermostats utilize sensors to determine the temperature outdoors and indoors. If a sensor fails, 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 resolve error code e1.

Honeywell Thermostat Error 11n

Error code 11n could appear if the thermostat is failing to recognize a heating or cooling unit. This might mean that the equipment itself is malfunctioning and unable to maintain a connection to the thermostat. This sometimes happens when the wiring is defective 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 poor electrical connection. When the wiring on your type of HVAC system is bad, the technician can replace it. When the thermostat itself is the source of the error code, it should probably be replaced.

Honeywell Thermostat Error e2

If you see error code e2 appear on your Honeywell smart thermostat, it could mean several different things. For example, one of the sensors that detects the temperature isn’t working properly. In other cases, it means the router was disconnected from its power source before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician will troubleshoot and replace the damaged sensor. If the problem stems from disconnected power, all you have to do is verify the router remains on over the course of the setup process.