Honeywell is a popular brand in the aerospace, building, performance material, and safety product industries. Thermostats are one of their products. Although many resellers provide fixing solutions for Honeywell thermostats, it is always fine to do it by yourself. But you should know Honeywell thermostat error codes. 

Honeywell Lyric™ T5 Wi-Fi thermostat and specific error codes 

Lyric T5 is a smart thermostat. It supports many virtual assistances in many ecosystems such as Amazon Alexa and Google assistance. You can control it from anywhere using a smartphone because it is Wi-Fi connected device. But the intelligence comfort control can control the temperature for maximum comfort. It has custom fan settings to circulate airflow as needed. This energy star certified Wi-Fi thermostat has a back-lit touchscreen display. Smart alerts remind you when it is time to change the filter. It will warn you if the indoor temperature is extreme. 

Honeywell Lyric™ T5 Wi-Fi thermostat specific error codes are below. 

Connection errors 

168: Wi-Fi radio error. A factory reset can solve the issue. Remember to power cycle the thermostat before resetting it. But if that does not work call lyric technical support at 800-633-3991. The unit could have developed a fault so the only solution is to replace it. 

399: No Internet detected. So, check your router and network settings. 

400: Failed to connect or find a Wi-Fi network. Wait until the thermostat connects to the network or check your hotspot. 

508: Wi-Fi is not set up. You can set up the Wi-Fi connection in the Lyric app. Open the app and follow the instructed procedure to connect your thermostat to clear the error code. 

Replacements 

181/182: A reminder to replace the filter. Install a new filter and then touch dismiss to clear the monitor. 

184: A reminder to replace the humidifier pad. Install a new humidifier pad and then touch dismiss to clear the monitor. 

185: A reminder to replace the dehumidifier filter. Install a new dehumidifier filter and then touch dismiss to clear the monitor. 

Other errors 

187: A remainder for replacing the ventilator filter. But you can clean and reuse it. After you are done either of them touch dismiss to clear the monitor. 

164: The error indicates that the heat pump requires service. Call service experts if you do not know how to do it. 

170: An internal memory error has occurred. Most of the time restarting if not resetting will solve the issue. But in case none of those has woke call Lyric technical support. 

171: You have not set the date and time. These data are compulsory for scheduling. So, set up the date and time. 

173: An issue with the temperature sensor of the thermostat. You can fix this by yourself. The sensor needs resetting. Press and hold the connect button on the sensor for 15 seconds. Now reconnect it within 2 feet away from the thermostat. Still, getting the error? Replace sensor batteries and try. Removing batteries for 30 seconds and re-inserting them is the final fix. In case you do want someone to fix it call lyric technical support. 

175: This means AC power restarted. It is not an error so you do not have to take any action. 

188/189: Install a new UV bulb. But if you do not want to do it by yourself, contact a service expert. 

210: You have not registered online for exterior temperature. This is an easy task via the Lyric app. By registering for the service thermostat can do more accurate operations. 

388: You have not registered online for remote access and outdoor temperature. This is an easy task via the Lyric app. By registering for the service thermostat can do more accurate operations. 

Honeywell T6 Pro Thermostat and specific error codes 

The Honeywell T6 Pro Smart Programmable Thermostat is a simple solution for your home but a combination of complex technologies to keep you comfortable. It is smart enough to learn your preferences and make a schedule of the best conditions. But if you do not like that or anytime you want a change, it is manually configurable. And you can do it from anywhere because the thermostat is connected to Wi-Fi. Geofencing allows the thermostat to save energy while you are in happy mode. 

Honeywell T6 Pro Smart Programmable Thermostat specific error codes are below. 

Connection errors 

168: Wi-Fi radio error. A factory reset can solve the issue. Remember to power cycle the thermostat before resetting it. But if that does not work call lyric technical support at 800-633-3991. The unit could have developed a fault so the only solution is to replace it. 

399: No Internet detected. So, check your router and network settings. 

400: Failed to connect or find a Wi-Fi network. Wait until the thermostat connects to the network or check your hotspot. 

508: Wi-Fi is not set up. You can set up the Wi-Fi connection in the Lyric app. Open the app and follow the instructed procedure to connect your thermostat to clear the error code. 

Replacements 

181/182: A reminder to replace the filter. Install a new filter and then touch dismiss to clear the monitor. 

183: A reminder to replace the water filter and clean the humidifier tank. After both of them are done touch dismiss to clear the monitor. 

184: A reminder to replace the humidifier pad. Install a new humidifier pad and then touch dismiss to clear the monitor. 

185: A reminder to replace the dehumidifier filter. Install a new dehumidifier filter and then touch dismiss to clear the monitor. 

187: A reminder to replace the ventilator filter. But you can clean and reuse it. After you are done either of them touch dismiss to clear the monitor. 

Sensor errors 

173: An issue with the temperature sensor of the thermostat. You can fix this by yourself. The sensor needs resetting. Press and hold the connect button on the sensor for 15 seconds. Now reconnect it within 2 feet away from the thermostat. Still, getting the error? Replace sensor batteries and try. Removing batteries for 30 seconds and re-inserting them is the final fix. In case you do want someone to fix it call lyric technical support. 

177: An issue with the indoor temperature sensor. Resetting can solve it but contact a service expert for a better fix. 

178: An issue with the outdoor temperature sensor. Resetting can solve it but contact a service expert for a better fix. 

Other errors 

164: The error indicates that the heat pump requires service. Call service experts if you do not know how to do it. 

170: An internal memory error has occurred. Most of the time restarting if not resetting will solve the issue. But in case none of those has woke call Lyric technical support. 

171: You have not set the date and time. These data are compulsory for scheduling. So, set up the date and time. 

175: This means AC power restarted. It is not an error, so you do not have to take any action. 

186: A remainder for washing the ventilator core. Then touch dismiss to clear the monitor.  

188/189: Install a new UV bulb. But if you do not want to do it by yourself, contact a service expert. 

210: You have not registered online for exterior temperature. This is an easy task via the Lyric app. By registering for the service thermostat can do more accurate operations. 

388: You have not registered online for remote access and outdoor temperature. This is an easy task via the Lyric app. By registering for the service thermostat can do more accurate operations. 

e1, 53, 89, 90 Honeywell thermostat error codes 

These error codes can be seen in the programmable Honeywell thermostat. Error code 53 is displayed when an outdoor sensor is not working. Investigate the sensor and the wiring. Can not see any problem? Try replacing the sensor. 

Error code 89 is displayed when it cannot detect a cooling or heating unit. Most of the time due to broken wires or any other fault in the wiring. If that does not work or you could not find any fault in the wiring replace a fuse in the outdoor compressor. 

Error code 90 is displayed when there is a fault in the thermostat module. The connection in the air handler unit is not strong. The Circuit board is a faulty one. 

Error code E1 or E is displayed with a code number on the right side. Error code and respective errors are below. 

23 – EIM is missing fossil fuel or electricity backup.  

29 – The device is trying to connect with Incompatible wireless units. 

30 – The zone number is invalid. 

33 – Fault in return Air Sensor wiring. Press and hold connect button for 10 seconds 

34 – Low signal. Reposition all wireless devices. 

38 – Replace batteries or reset. Stay at least 6 feet away from the EIM. 

53 – Outdoor Temperature and outdoor Humidity data not detected. 

You can download the official documentation for further clarifications. Lyric™ T5 User Guide and T6 Pro Smart User Guide. 

I hope this article helps you. See here for more technical stuff