Error Code E42: How to Fix This Honeywell Thermostat Code

A Honeywell smart thermostat is an excellent way to optimize how you use your heating and cooling. But like any utility, you could occasionally run into a problem. With the digital display, Honeywell smart thermostats can provide an error code that trained technicians will use to get a better sense of what's wrong. Here are some of the most common error codes you may see on your Honeywell smart thermostat.

Honeywell Thermostat Error e42

You can see this error code when your home’s Wi-Fi connection did not provide an IP address for the thermostat to connect with. This can occur if your router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This process automatically supplies the needed IP address for your thermostat to link up.

How to Fix Honeywell Thermostat Error e42

You can clear error code e42 by verifying that your router is enabled for DHCP. When it does, you may also need to power cycle the router and perform the setup process again with the thermostat. This should see to it that the DHCP is delivered and connects to the smart thermostat.

Honeywell Error Code e02

Error code e02 appears whenever 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 try the password again.

How to Fix Honeywell Thermostat Error e02

All you'll need to do to resolve error e02 is ensure you’re typing the correct Wi-Fi password when setting up the thermostat.

Error Code 40 for Honeywell Thermostats

Error code 40 can show up when the thermostat is alerted that a heat pump or air conditioner’s monitoring system has detected a malfunction. Most commonly, this occurs when the compressor isn’t running despite being instructed to. But this error code could also show up if power is disconnected from the outdoor unit for a lengthy period of time. A “High Pressure Fault” error, caused by blocked airflow, can lead to this error code. Lastly, you might encounter 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 normal operation. If you restart the thermostat and error code 40 reappears, it's time to get a hold of an experienced technician.

Honeywell Error Code e43

If the Honeywell thermostat displays error code e43, it can’t communicate with the router, and by extension the 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 a short period. The thermostat could also be disconnected if you recently switched the password or the Wi-Fi’s SSID, which is the name you give it.

Honeywell Error Code e1

Thermostats employ sensors to determine the temperature outdoors and indoors. If a sensor breaks down, you could see error code e1 turn up 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 clear error code e1.

Honeywell Thermostat Error 11n

Error code 11n may appear in situations where the thermostat can’t recognize a heating or cooling unit. This can mean that the equipment itself is malfunctioning and unable to communicate with the thermostat. This sometimes happens when the wiring is defective or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can utilize a voltmeter to assess if there’s a faulty 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 problem, it should probably be replaced.

Error Code e2 for Honeywell Thermostats

If you’ve noticed error code e2 appear on your Honeywell smart thermostat, it could mean several different things. In some cases, one of the sensors responsible for detecting the temperature isn’t working correctly. In other cases, 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

If the error code stems from sensor failure, a technician can troubleshoot and replace the impacted sensor. When the problem stems from disconnected power, all you'll need to do is see to it that the router stays on during the setup process.