Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is a great way to optimize how you use your heating and cooling. But like any utility, you may occasionally experience a problem. With the digital display, Honeywell smart thermostats can show an error code that professional technicians can use to understand what's going on. Here are some of the most known error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might receive this error code in the event that your home’s Wi-Fi connection did not present an IP address for the thermostat to hook up to. This can occur if the router does not execute the Dynamic Host Configuration Protocol, or DHCP. This function automatically transmits the required IP address for your thermostat to connect.

How to Fix Honeywell Thermostat Error e42

You can fix error code e42 by making sure that your router is enabled for DHCP. Assuming it does, you might also have to power cycle the router and complete the initial setup process again with the thermostat. This should see to it that the DHCP is delivered and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 occurs if the password for communicating with your home’s Wi-Fi router is not correct. When this error code has appeared 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 ensure you’re entering the correct Wi-Fi password when configuring the thermostat.

Honeywell Thermostat Error 40

Error code 40 can show up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most commonly, this appears when the compressor isn’t working despite being directed to. But this error code may also surface if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, induced by poor airflow, can display this error code. Finally, you may experience error code 40 if there’s an issue 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, it’s best to contact 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 could 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 about 30 seconds. The thermostat might also be disconnected if you have recently updated 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 fails, you may see error code e1 turn up on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n may appear when the thermostat is failing to recognize a heating or cooling unit. This may mean that the equipment itself is malfunctioning and unable to connect with the thermostat. This sometimes happens when the wiring is damaged or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can use a voltmeter to assess if there’s a faulty electrical connection. If the wiring on your specific HVAC equipment is bad, the technician can replace it. When the thermostat itself is the source of the error code, it will likely have to be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 appear on your Honeywell smart thermostat, it can mean a few different things. In some cases, one of the sensors that detects 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 is caused by sensor failure, a technician will troubleshoot and switch out the affected sensor. If 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.