How to Resolve These Seven Error Codes on Your Nest Thermostat

August 15, 2022

Operating a Nest thermostat is one of the most convenient ways to optimize the day-to-day schedule of your heating and cooling. This smart thermostat can learn your preferences and automatically make improvements. But as you may expect, it won’t work correctly or at all if you see an error code show up. The precise error code offers useful information about the underlying problem, something a professional technician can use to provide solutions that much sooner.

Here are seven of the most frequent error codes you may encounter on your Nest thermostat. We’ll review the basics of each error code along with how you could address it and the estimated cost to do so. Don't forget that while the costs will ultimately depend on the exact Nest model, you can count on paying around $75-$200 for repairs. This should include things like travel and labor costs on top of any specific hardware required to complete repairs.

e298 - Critical

This critical error code is limited to newer models of the Nest thermostat and appears when the power is shut off. Because this is a critical power error, the thermostat will change to the backup battery system. The error message will remain on display until the issue is resolved.

Losing power to your Nest thermostat can be for several reasons. The wiring could have disconnected or become damaged, or a disconnection might have occurred further along in your electrical system. This may be the circuit breaker, fuse box or system switch. A professional technician should inspect electrical connections and wiring until they find the source of the problem.

e294 - Critical

Critical error code e294 shows up when your Nest thermostat’s wiring has to be reconfigured. More specifically, you’ll need the technician to reconfigure the R wire. They’ll first perform a factory reset of your thermostat to ensure it’s not just a software error. If that doesn’t work, they’ll check the wiring diagram of the thermostat and start checking connectors.

They’ll shut off the power and gradually check each wire, ensuring they are fully inserted into the connector with the correct amount of bare copper. After they find the malfunctioning connector, it can be swapped for a new one.

e195 - Critical

This critical error code can appear when the weather outside is severely hot. The HVAC system can break down and stop sending power to your Nest thermostat. When this problem lingers, the backup battery in your thermostat drains and the thermostat will eventually turn off. Presuming the breakers are on, you can inspect a couple of other places before consulting a professional technician.

As this error can drain your thermostat’s battery, the first step might be providing enough power to find out if this specific error code is what you’re working with. You can separate the thermostat from its base and provide power through a USB cable. Assuming it displays error code 195, you may continue to visually check components like the wiring as well as your air conditioner’s air filter or drainage system. If you struggle to find anything wrong with these components, it will likely be best to call a pro.

e103 - Critical

Another critical error code, e103 signifies an electrical error with your Nest thermostat. More specifically, e103 will refer to an overcurrent problem, which means the wiring is getting more power than what is safe and normal. This may stem from the breaker box, an error from the control board or through a defective connection in the thermostat. Your technician will cautiously investigate and test the Nest’s electrical system to determine where the power is surging or why the thermostat is convinced there’s an overcurrent problem.

n260

While this error code isn’t critical, it could still keep you from using the Nest thermostat how you want to. Error code n260 concerns the lack of a C wire or Nest Power Connector, as missing one can block your Nest from receiving enough power. You can inspect the Nest’s C connector for the presence of a C wire and adapt the wiring itself if there is. If not, you’ll need a Nest Power Connector.

During installation of a Nest Power Connector, you might notice error code E297 show up. This can be resolved by updating your thermostat in Settings -> Software -> Update. If the Power Connector is already installed, you’ll instead be required 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 originating from an overcurrent. If excess power is transported inside the Nest’s wiring, it can damage internal components and may even be a fire hazard. If you see this error code pop up on your Nest thermostat and want to take steps to prevent electrical damage, it’s a good idea to turn the power off straightaway. You can then get in touch with a professional technician with the necessary experience identifying and fixing electrical damage.

e73 - Critical

When your thermostat displays error code e73, it indicates that the Rc wire is not getting power. This might be as simple as the breaker being switched off, but it may also be something with the wiring. After switching off the power to your HVAC system and thermostat, you can visually inspect the wires to make sure they’re not loose or damaged. If nothing looks to be out of place, it’s a good idea to contact a local professional.