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 could occasionally experience a problem. With its digital display, Honeywell smart thermostats can show an error code that professional technicians use to get a better sense of what's happening. Here are a few of the most likely error codes you could 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 connect to. This can happen if a router does not perform the Dynamic Host Configuration Protocol, or DHCP. This process 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 making sure that your router is enabled for DHCP. If it does, you might also need 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 the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 is displayed whenever the password for communicating with your home’s Wi-Fi router is incorrect. When this error code is displayed for 30 seconds, the thermostat’s digital display should automatically transition to the Wi-Fi setup screen so you can try to enter the password again.

How to Fix Honeywell Thermostat Error e02

All you have to do to solve 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 alerted that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most commonly, this occurs once the compressor isn’t turning on despite being instructed to. But this error code could also appear if power is disconnected from the outdoor unit for an extended period of time. A “High Pressure Fault” error, induced by obstructed airflow, can lead to this error code. And finally, you may 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 examine the air filter for signs of a clog, as well as the breakers and indoor unit’s blower for regular operation. If you reset the thermostat and error code 40 reappears, you should try to contact an experienced technician.

Honeywell Thermostat Error e43

If a Honeywell thermostat presents error code e43, it is failing to 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

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

Honeywell Thermostat Error e1

Thermostats utilize sensors to identify the temperature outdoors and indoors. If a sensor breaks down, you might see error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

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

Honeywell Thermostat Error 11n

Error code 11n could appear if the thermostat can’t connect to 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 damaged or even if the thermostat has failed.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can use a voltmeter to find out if there’s a faulty electrical connection. If the wiring on your type of 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 notice error code e2 pop up on your Honeywell smart thermostat, it might mean a couple of different things. In some cases, one of the sensors used to detect 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

If the error code is caused by sensor failure, a technician will troubleshoot and replace the impacted sensor. If the problem originates from disconnected power, all you have to do is see to it that the router stays on over the course of the setup process.