Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an easy way to better manage how you use your home comfort system. But like any utility, you might occasionally run across a problem. With a digital display, Honeywell smart thermostats can display an error code that certified technicians can use to understand what's happening. Here are some of the most known error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can see this error code if 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 execute the Dynamic Host Configuration Protocol, or DHCP. This process automatically sends out the needed IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by verifying that your router can complete the DHCP. If it does, you might also have to power cycle the router and perform the setup process again with your thermostat. Doing so should ensure the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed if the password for connecting to your home’s Wi-Fi router was incorrect. When this error code is displayed for 30 seconds, the thermostat’s digital display automatically transitions to the Wi-Fi setup screen so you can try 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 appear 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 working despite being instructed to. But this error code may also surface if power is shut off from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, induced by blocked airflow, can render this error code. And finally, you could see 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 regular operation. If you turn the thermostat off and on again and error code 40 reappears, it's time to get in touch with 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 the Wi-Fi. This might 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

Restart the router by unplugging it and leaving it that way for around 30 seconds. The thermostat could also be disconnected if you 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 detect the temperature outdoors and indoors. If a sensor malfunctions, you might notice error code e1 show up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A trained technician can change out the sensor and restart the thermostat, which should clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n can appear if the thermostat is failing 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 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 employ a voltmeter to assess if there’s a bad electrical connection. When the wiring on your specific 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 pop up on your Honeywell smart thermostat, it might mean a couple of different things. Sometimes, one of the sensors responsible for detecting the temperature isn’t working properly. In other cases, it means the router was disconnected from its power source before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code is a result of sensor failure, a technician should troubleshoot and switch out the impacted sensor. Any time the problem stems from disconnected power, all you have to do is verify the router remains on throughout the setup process.