Solved: Honeywell Thermostat Error Codes

November 08, 2022

A Honeywell smart thermostat is an excellent way to optimize how you use your heating and cooling. But like any technology, you might sometimes run across a problem. With a digital display, Honeywell smart thermostats can provide an error code that certified technicians can use to get a better sense of what's wrong. Here are a few of the most known error codes you could see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You may receive this error code if your home’s Wi-Fi connection did not supply an IP address for the thermostat to hook up to. This can happen if your router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This process automatically supplies the required IP address for your thermostat to connect to the Wi-Fi.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by confirming that your router has enabled DHCP. When it does, you may also need to power cycle the router and complete the initial setup process again with your thermostat. Completing this task should ensure the DHCP is transmitted and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears whenever the password for communicating with your home’s Wi-Fi router is not correct. After this error code has appeared 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 ensure you’re entering the correct Wi-Fi password when setting up the thermostat.

Honeywell Thermostat Error 40

Error code 40 can show up when the thermostat is informed that a heat pump or air conditioner’s monitoring system has identified a malfunction. Most commonly, this happens once 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 an extended period of time. A “High Pressure Fault” error, induced by obstructed airflow, can render this error code. Finally, you might see error code 40 if there’s something wrong 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 normal operation. If you restart the thermostat and error code 40 reappears, it’s best to get a hold of an experienced technician.

Honeywell Thermostat Error e43

If your Honeywell thermostat displays error code e43, it is failing to communicate with the router, and by extension the 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 about 30 seconds. The thermostat may also be disconnected if you 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 detect the temperature outdoors and indoors. If a sensor fails, you might notice error code e1 appear 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 take care of error code e1.

Honeywell Thermostat Error 11n

Error code 11n could appear if the thermostat is failing to detect a heating or cooling unit. This might mean that the equipment itself is malfunctioning and unable to maintain a connection to the thermostat. This sometimes happens when the wiring is damaged or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can use a voltmeter to determine if there’s a bad electrical connection. In situations where the wiring on your existing HVAC system is bad, the technician can replace it. In situations where the thermostat itself is the source of the error code, it should probably be replaced.

Honeywell Thermostat Error e2

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it could mean a couple of 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 the outlet before the thermostat completed the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code stems from sensor failure, a technician will troubleshoot and swap out the affected sensor. If the problem stems from disconnected power, all you’ll have to do is make sure the router stays on throughout the setup process.