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Thermostat error codes always mean something specific. If you’re seeing a strange code on your thermostat’s display but can’t figure out the meaning of it, there’s no need to worry. We have compiled a list of error codes so that you can understand what your Honeywell thermostat is trying to tell you. Check it out below!

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What are error codes?

Think of error codes as a way for your thermostat to communicate if something is wrong. If you know how to interpret the error code that is being shown on your thermostat’s display, you are then able to correctly address the issue and fix it. Error codes are extremely useful and can even help maintain a healthy and efficient HVAC system thanks to the wide variety of alerts, reminders, and notifications.

Are error codes specific to the model?

Error codes are usually manufacturer-specific. However, if the manufacturer is the same, many error codes are identical for multiple models while some are specific to each model. Here we list the error codes that are generic and the same for most Honeywell thermostats. We recommend checking your thermostat model by identifying the model number. This way, you can be certain that you are correctly analyzing the error code shown on your thermostat’s display.

Common Honeywell thermostat error codes

164Problem: Heat Pump
Details: It indicates that there’s a problem with your heat pump that most likely needs servicing. Contact your HVAC technician for this purpose.
168Problem: Wi-Fi Radio  
Details: This error shows that the Wi-Fi module is not working anymore and wireless connectivity is not available. You’ll need to contact your HVAC technician for professional help.
170Problem: Internal Memory 
Details: This error means that the internal memory card of the thermostat has come across an error. Please contact your HVAC technician and check whether the memory chip needs to be replaced.
171Problem: Date and Time
Details: This error reminds you to set the correct date and time so you can make use of your thermostat’s features like presets/programs and scheduling.
173Problem: Temperature Sensor 
Details: This error indicates that the integrated temperature sensor is not working. Contact your HVAC technician and check whether this can be fixed or if you need a replacement.
175Problem: AC Power
Details: This error is usually displayed after a power outage or blackout. It clearly shows that the AC power has been resumed and it does not require any further action. 
177Problem: Indoor Temperature Sensor
Details: If you see this error, it means that the indoor temperature sensor of the thermostat is either disconnected or not wired properly. Seek professional assistance from your HVAC technician.
178Problem: Outdoor Temperature Sensor
Details: If you see this error, it means that the outdoor temperature sensor of the thermostat is either disconnected or not wired properly. Seek professional assistance from your HVAC technician.
181/182Problem: Air Filter 
Details: This error shows that the air filter should be substituted with a new one. Contact a professional HVAC technician to get this done. You can dismiss the warning once you’ve replaced it.
183Problem: Humidifier Tank and Water Filter
Details: This error clearly states that the humidifier tank needs a thorough cleaning and the water filter needs to be replaced. Do the cleaning yourself or ask an HVAC technician to take care of both issues. 
184Problem: Humidifier Pad
Details: This error shows that you need to replace the humidifier pad. This can be a DIY job or you can contact a professional HVAC technician to get it done. 
185Problem: Dehumidifier Filter
Details: This error indicates that you need to replace the dehumidifier filter. This can be a DIY job or you can contact a professional HVAC technician to get it done. 
186Problem: Ventilator Core
Details: This error means that you need to clean the ventilator core. This can be a DIY job or you can contact a professional HVAC technician to get it done. 
187Problem: Ventilator Filter
Details: This error indicates that you need to clean or replace the ventilator filter. This can be a DIY job or you can contact a professional HVAC technician to get it done.
188Problem: UV Bulb
Details: This error shows that you need to replace the UV bulb. This can be a DIY job or you can contact a professional HVAC technician to get it done. 
189Problem: UV Bulb
Details: This error shows that you need to replace the UV bulb. This can be a DIY job or you can contact a professional HVAC technician to get it done. 
210Problem: Online Registration for Outdoor Temperature
Details:  If you want to get up-to-date outdoor weather temperature, you need to get connected and register your thermostat online. This can be done through the dedicated Lyric smartphone app developed by the manufacturer.
388Problem: Online Registration for Remote Access and Outdoor Temperature
Details:  To be able to remotely access your temperature and also get access to an accurate outdoor temperature, you need to register your thermostat. Use the Lyric smartphone app developed by the manufacturer to get this done.
399Problem: No Internet
Details: This error indicates that your internet connection has been lost. Contact your network provider and address this issue or check your local network settings.
E01Problem: Wi-Fi Setup
Details: If you encounter this error, make sure your router is connected to a power source while trying to connect to a network.
E02Problem: Invalid Wi-Fi password
Details: This error indicates that you have entered an invalid Wi-Fi password. Ensure you re-enter the correct password for your Wi-Fi network and try again. If you still get this error, consider changing your password.
E42Problem: IP address
Details: If the router cannot assign an IP address to the thermostat, verify that the router is correctly set up to issue IP addresses automatically.
E43Problem:  Problem in communicating with Total Connect Comfort
Details: This error indicates that your Internet connection has been lost and the thermostat cannot connect to the Total Connect Comfort app. Check with your internet provider.
E99Problem: General error
Details: If you encounter this error, remove the thermostat and reconnect it after a few minutes.

Model specific error codes

If you have gone through the list above but still cannot find the code you have been looking for, it is probably a model-specific code. You can check what it means by referring to the User Manual of your specific thermostat. Each model comes with its own manual and can be downloaded from here.

Conclusion

Dealing with error codes and trying to solve different issues related to your heating and cooling system can sometimes be a tedious and time-consuming task. That’s why we have compiled the list above. We hope you find the information presented useful in helping you understand the language that your thermostat speaks!

Sources

Honeywell

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