Solved: Honeywell Thermostat Error Codes

November 08, 2022

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

Honeywell Thermostat Error e42

You can see this error code when your home’s Wi-Fi connection did not provide an IP address for the thermostat to hook up to. This can take place if the router does not perform the Dynamic Host Configuration Protocol, or DHCP. This function automatically transmits the needed 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 is enabled for DHCP. When it does, you may also have to power cycle the router and perform the setup process again with the thermostat. Doing so should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears if the password for communicating with your home’s Wi-Fi router is incorrect. Once this error code is displayed for 30 seconds, the thermostat’s digital display should automatically transition to the Wi-Fi setup screen so you can try the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to clear error e02 is make sure you’re putting in 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 if the compressor isn’t working despite being directed to. But this error code can also surface if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, triggered by obstructed airflow, can display this error code. Lastly, you might experience error code 40 if there’s an issue with the coolant, 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 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 shows error code e43, it is unable to 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

Reboot the router by unplugging it and leaving it that way for around 30 seconds. The thermostat could also be disconnected if you recently switched the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Thermostat Error e1

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

How to Fix Honeywell Thermostat Error e1

A skilled technician can replace the sensor and restart the thermostat, which should resolve error code e1.

Honeywell Thermostat Error 11n

Error code 11n can appear when the thermostat is failing to connect to a heating or cooling unit. This might mean that the equipment itself is faulty and unable to connect with 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 licensed technician can use a voltmeter to find out if there’s a poor electrical connection. When the wiring on your type of HVAC equipment is bad, the technician can replace it. When the thermostat itself is the problem, it should probably be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 appear on your Honeywell smart thermostat, it might mean a few different things. Sometimes, 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 is caused by sensor failure, a technician can troubleshoot and replace the impacted sensor. If the problem comes from disconnected power, all you’ll have to do is see to it that the router stays on during the setup process.