Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is a great way to optimize how you use your home comfort system. But like any mechanical system, you might sometimes run into a problem. With its digital display, Honeywell smart thermostats can provide an error code that trained technicians can use to understand what's going on. Here are several of the most likely error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might see this error code if your home’s Wi-Fi internet did not provide an IP address for the thermostat to hook up to. This can occur if the router fails to complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the necessary IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router is enabled for DHCP. If it does, you may also have to power cycle the router and repeat the initial setup process with the thermostat. This should see to it that the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs when the password for communicating with your home’s Wi-Fi router is incorrect. After this error code is displayed 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'll need to do to clear error e02 is verify you’re putting in the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

Error code 40 can appear when the thermostat is informed that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most often, this occurs if the compressor isn’t turning on despite being directed to. But this error code could also surface if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, triggered by blocked airflow, can display this error code. And finally, you could experience 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 ordinary operation. If you turn the thermostat off and on again and error code 40 reappears, you should try to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat shows error code e43, it is failing to communicate with the router, and by extension the 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

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

Honeywell Thermostat Error e1

Thermostats utilize sensors to detect 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 swap out the sensor and reset the thermostat, which should take care of error code e1.

Honeywell Thermostat Error 11n

Error code 11n can appear when the thermostat is failing to detect a heating or cooling unit. This might mean that the equipment itself is malfunctioning 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 licensed technician can employ a voltmeter to find out if there’s a bad electrical connection. When the wiring on your existing HVAC equipment is bad, the technician can replace it. When the thermostat itself is the problem, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you see 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 operating 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

If the error code is a result of 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 verify the router stays on over the course of the setup process.