Operating a Nest thermostat is one of the most convenient ways to optimize the day-to-day schedule of your HVAC system. This smart thermostat can learn your preferences and automatically make adjustments. But as you might expect, it won’t work correctly or at all if you see an error code show up. The exact error code offers useful information about the root of the problem, something a professional technician can use to provide solutions that much faster.
Here are seven of the most likely error codes you may encounter on your Nest thermostat. We’ll review the basics of each error code on top of how you can fix it and the approximate cost to do so. Don't forget that while the costs will ultimately be dependent on the precise Nest model, you can expect to pay about $75-$200 for repairs. This should also cover travel and labor costs on top of any specific components needed to finish repairs.
e298 - Critical
This critical error code is limited to new models of the Nest thermostat and appears when the power is shut off. Because this is a critical power error, the thermostat will switch to the backup battery system. The error message will continue to be displayed until the problem is dealt with.
Losing power to your Nest thermostat can be for a number of reasons. The wiring could have disconnected or become damaged, or a disconnection could have happened further along in your home's electrical system. This may be the circuit breaker, fuse box or system switch. A professional technician should examine electrical connections and wiring until they locate the root of the problem.
e294 - Critical
Critical error code e294 appears when your Nest thermostat’s wiring needs to be reconfigured. More specifically, the technician should reconfigure the R wire. They’ll first conduct a factory reset of your thermostat to make sure it’s not merely a software problem. If that doesn’t work, they’ll examine the wiring diagram of the thermostat and begin checking connectors.
They’ll shut off the power and gradually look at each wire, ensuring they are fully placed into the connector with the correct amount of exposed copper. When they locate the problem connector, it can be swapped for a new one.
e195 - Critical
This critical error code can surface when the weather outside is especially hot. The HVAC system can break down and stop sending power to your Nest thermostat. When this problem lasts, the backup battery in your thermostat depletes and the thermostat will finally turn off. Presuming the breakers are on, you can examine a few other places before consulting a professional technician.
As this error can consume your thermostat’s battery, the first step might be providing enough power to find out if this specific error code is what you’re facing. You can detach the thermostat from its base and supply power by using a USB cable. If it presents error code 195, you should continue to visually inspect components such as the wiring as well as your air conditioner’s air filter or drainage system. If you can't detect anything wrong with these components, it will likely be best to get in touch with a pro.
e103 - Critical
Another critical error code, e103 indicates an electrical error with your Nest thermostat. More specifically, e103 may refer to an overcurrent problem, which means the wiring is getting more power than needed. This may stem from the breaker box, an error from the control board or thanks to a faulty connection in the thermostat. Your technician needs to carefully investigate and test the Nest’s electrical system to understand where the power is surging or why the thermostat is convinced there’s an overcurrent problem.
Although this error code isn’t critical, it may still keep you from using the Nest thermostat like normal. Error code n260 refers to the lack of a C wire or Nest Power Connector, as not having one can block your Nest from obtaining sufficient power. You can check the Nest’s C connector for the presence of a C wire and adjust the wiring itself if there is. If not, you need a Nest Power Connector.
With installation of a Nest Power Connector, you may notice error code E297 be displayed. This can be remedied by updating your thermostat in Settings -> Software -> Update. If the Power Connector was already installed, you’ll instead need to update the wiring info in the app from Settings -> Thermostat -> Wiring -> Update wiring.
e104 - Critical
Similar to error code e103, e104 is a critical error stemming from an overcurrent. If excess power is sent using the Nest’s wiring, it could damage internal components and may even be a fire hazard. If you see this error code show up on your Nest thermostat and want to take steps to prevent electrical damage, it’s a good idea to switch the power off straightaway. You can then get a hold of a professional technician with the appropriate experience diagnosing and fixing electrical problems.
e73 - Critical
When your thermostat displays error code e73, it means that the Rc wire is not receiving power. This could be as easy as the breaker being switched off, but it may also be an issue with the wiring. After turning off the power to your HVAC system and thermostat, you can visually inspect the wires to make sure none of them are loose or damaged. If nothing appears to be out of place, it’s a good idea to speak with a local professional.