Solved! Error Code E42 for Honeywell Smart Thermostats

A Honeywell smart thermostat is an excellent way to optimize how you use your home comfort system. But like any utility, you might sometimes run across a problem. With its digital display, Honeywell smart thermostats can show an error code that trained technicians can use to get a better sense of what's wrong. Here are some of the most known error codes you could see on your Honeywell smart thermostat.

Honeywell Error Code e42

You can see this error code in the event that your home’s Wi-Fi internet did not supply an IP address for the thermostat to connect to. This can occur if a router doesn't perform the Dynamic Host Configuration Protocol, or DHCP. This function automatically transmits the required IP address for your thermostat to link up.

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 might also have to power cycle the router and repeat the initial setup process with your thermostat. This should ensure the DHCP is sent and connects to your smart thermostat.

Honeywell Thermostat Error e02

Error code e02 appears when 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 should automatically transition 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 clear error e02 is make sure you’re entering the correct Wi-Fi password when configuring the thermostat.

Honeywell Error Code 40

Error code 40 can pop up when the thermostat is notified that a heat pump or air conditioner’s monitoring system has recognized a malfunction. Most often, this appears when the compressor isn’t running despite being directed to. But this error code could also appear if power is shut off from the outdoor unit for an extended period of time. A “High Pressure Fault” error, caused by obstructed airflow, can display this error code. Finally, you could experience error code 40 if there’s a problem 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 regular operation. If you reset the thermostat and error code 40 reappears, it's time to contact an experienced technician.

Honeywell Error Code e43

If your Honeywell thermostat presents error code e43, it is unable to 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

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

Error Code e1 for Honeywell Thermostats

Thermostats use sensors to detect the temperature outdoors and indoors. If a sensor malfunctions, you may see error code e1 appear on your Honeywell smart thermostat.

How to Fix Honeywell Thermostat Error e1

A qualified technician can swap out the sensor and restart the thermostat, which should take care of error code e1.

Error Code 11n for Honeywell Thermostats

Error code 11n could appear if the thermostat is unable to detect a heating or cooling unit. This might mean that the equipment itself is faulty and unable to communicate with the thermostat. This can happen when the wiring is bad or even if the thermostat is faulty.

How to Fix Honeywell Thermostat Error 11n

A licensed technician can utilize a voltmeter to find out if there’s a faulty electrical connection. When the wiring on your specific HVAC system is bad, the technician can replace it. If the thermostat itself is the issue, it should probably be replaced.

Honeywell Error Code e2

If you’ve noticed error code e2 pop up on your Honeywell smart thermostat, it might mean several different things. Sometimes, one of the sensors that detects the temperature isn’t operating properly. In other cases, it means the router was disconnected from power before the thermostat could complete the setup process.

How to Fix Honeywell Thermostat Error e2

In situations where the error code stems from sensor failure, a technician can troubleshoot and replace the affected sensor. When the problem stems from disconnected power, all you’ll have to do is verify the router remains on throughout the setup process.