How to Resolve These Seven Error Codes on Your Nest Thermostat

August 15, 2022

Operating a Nest thermostat is one of the best ways to optimize the day-to-day schedule of your comfort system. This smart thermostat can learn your preferences and automatically make improvements. But as you may expect, it won’t work properly or at all if you see an error code show up. The exact error code provides useful information about the source of the problem, something a professional technician can use to offer solutions that much faster.

Here are seven of the most frequent error codes you might encounter on your Nest thermostat. We’ll walk you through the basics of each error code as well as how you might fix it and the projected cost to do so. Don't forget that while the costs will ultimately be dependent on the specific Nest model, you can count on paying between $75-$200 for repairs. This should include things like travel and labor costs along with any specific components needed to complete repairs.

e298 - Critical

This critical error code is limited to the latest models of the Nest thermostat and is displayed 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 remain on display until the problem is resolved.

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

e294 - Critical

Critical error code e294 appears when your Nest thermostat’s wiring should be reconfigured. More specifically, you’ll need the technician to reconfigure the R wire. They’ll first complete a factory reset of your thermostat to make sure it’s not just a software issue. If that doesn’t work, they’ll examine the wiring diagram of the thermostat and start checking connectors.

They’ll detach the power and progressively check each wire, making sure they are fully inserted into the connector with the proper amount of uncovered copper. Once they find the problem connector, it can be replaced for a new one.

e195 - Critical

This critical error code can surface when the weather outside is particularly hot. The HVAC system can shut down and stop sending power to your Nest thermostat. When this problem lingers, the backup battery in your thermostat depletes and the thermostat will eventually power down. In the event the breakers are on, you can examine a handful of other places before consulting a professional technician.

As this error can drain your thermostat’s battery, the first step might be restoring enough power to figure out if this specific error code is what you’re facing. You can detach the thermostat from its base and deliver power by using a USB cable. In the event it reveals 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 don’t find anything wrong with these components, it will probably be best to contact a pro.

e103 - Critical

Another critical error code, e103 signifies an electrical error with your Nest thermostat. More specifically, e103 may refer to an overcurrent problem, which means the wiring is receiving more power than what is safe and normal. This may stem from the breaker box, an error from the control board or through a faulty connection in the thermostat. Your technician should meticulously examine and test the Nest’s electrical system to figure out where the power is surging or why the thermostat believes there’s an overcurrent problem.

n260

Although this error code isn’t critical, it might still stop 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 getting enough power. You can inspect the Nest’s C connector for the presence of a C wire and adjust the wiring itself if there is. If not, you can get a Nest Power Connector.

Due to installation of a Nest Power Connector, you will sometimes notice error code E297 show up. This can be dealt with by updating your thermostat in Settings -> Software -> Update. If the Power Connector has already been installed, you’ll instead have 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 being delivered through the Nest’s wiring, it may damage internal components and can even be a fire hazard. If you see this error code appear on your Nest thermostat and want to take steps to prevent electrical damage, it’s recommended to shut the power off straightaway. You can then contact a professional technician with the necessary experience detecting and fixing electrical damage.

e73 - Critical

When your thermostat displays error code e73, it means that the Rc wire is not getting power. This may be as easy as the breaker being turned off, but it could also be an issue with the wiring. After switching 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 seems to be out of place, it’s a good idea to get in touch with a local professional.