Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an easy way to better manage how you use your heating and cooling. But like any utility, you might sometimes run across a problem. With its digital display, Honeywell smart thermostats can provide an error code that certified technicians will use to understand what's happening. Here are a few of the most likely error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can encounter this error code in the event that your home’s Wi-Fi connection did not provide an IP address for the thermostat to hook up to. This can occur if the router does not perform 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 making sure that your router can complete the DHCP. Assuming it does, you might also have to power cycle the router and complete the initial setup process again with your thermostat. This should ensure the DHCP is delivered and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs whenever the password for connecting to 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 attempt to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to resolve 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 alerted that a heat pump or air conditioner’s monitoring system has detected a malfunction. For the most part, this occurs if the compressor isn’t working despite being instructed to. But this error code could also surface if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, caused by obstructed airflow, can render this error code. 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 check the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for regular operation. If you restart 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 can’t communicate with the router, and by extension your 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 a short period. The thermostat might also be disconnected if you have recently changed the password or the Wi-Fi’s SSID, which is the name you create for it.

Honeywell Thermostat Error e1

Thermostats utilize sensors to identify the temperature outdoors and indoors. If a sensor fails, you could notice error code e1 show up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n may appear in situations where the thermostat is failing to detect a heating or cooling unit. This might mean that the equipment itself is faulty and unable to maintain a connection to the thermostat. This can happen when the wiring is damaged or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can use a voltmeter to assess if there’s a faulty electrical connection. In situations where the wiring on your specific HVAC equipment is bad, the technician can replace it. In situations where the thermostat itself is the problem, it should probably be replaced.

Honeywell Thermostat Error e2

If you notice error code e2 pop up on your Honeywell smart thermostat, it might mean a few different things. For example, one of the sensors responsible for detecting the temperature isn’t working correctly. In other instances, 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

In situations where the error code stems from sensor failure, a technician will troubleshoot and switch out the affected sensor. When the problem comes from disconnected power, all you’ll have to do is see to it that the router stays on over the course of the setup process.