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 mechanical system, you may occasionally experience a problem. With a digital display, Honeywell smart thermostats can display an error code that trained technicians can use to figure out what's going on. Here are some of the most common error codes you might see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You might encounter this error code when your home’s Wi-Fi internet did not supply an IP address for the thermostat to connect with. This can take place if a router does not complete the Dynamic Host Configuration Protocol, or DHCP. This procedure automatically transmits the necessary IP address for your thermostat to connect to the Wi-Fi.

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 usually also need to power cycle the router and perform the setup process again with your thermostat. This should see to it that the DHCP is sent and connects to the smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears if the password for communicating with your home’s Wi-Fi router was incorrect. Once 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 need to do to solve error e02 is verify you’re putting in the correct Wi-Fi password when configuring 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 recognized a malfunction. Most often, this happens if the compressor isn’t working despite being directed to. But this error code can also show up if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, triggered by poor airflow, can render this error code. Lastly, you could experience error code 40 if there’s something wrong with the refrigerant, 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 ordinary 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 shows 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

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

Honeywell Thermostat Error e1

Thermostats use sensors to detect the temperature outdoors and indoors. If a sensor breaks down, you could notice 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 in situations where the thermostat is unable to connect to a heating or cooling unit. This may mean that the equipment itself is faulty and unable to connect with the thermostat. This can happen when the wiring is defective or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A qualified technician can employ a voltmeter to assess if there’s a poor electrical connection. In situations where the wiring on your existing HVAC equipment 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 notice error code e2 pop up on your Honeywell smart thermostat, it might mean a few different things. For example, one of the sensors that detects the temperature isn’t working properly. In other cases, it means the router was disconnected from the outlet before the thermostat finished the setup process.

How to Fix Honeywell Thermostat Error e2

If the error code is a result of sensor failure, a technician will troubleshoot and replace the impacted sensor. Any time the problem stems from disconnected power, all you’ll have to do is make sure the router stays on throughout the setup process.