How to Resolve These Seven Error Codes on Your Nest Thermostat

August 15, 2022

Installing a Nest thermostat is one of the easiest ways to optimize the everyday 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 appear. The specific error code provides useful information about the root of the problem, something a knowledgeable technician can use to provide solutions that much faster.

Listed below are seven of the most likely error codes you might find on your Nest thermostat. We’ll walk you through the basics of each error code along with how you might fix it and the estimated cost to do so. Don't forget that while the price will ultimately hinge on the precise Nest model, you can expect to pay around $75-$200 for repairs. This should also cover travel and labor costs along with any specific parts needed to finish repairs.

e298 - Critical

This critical error code is limited to newer models of the Nest thermostat and appears when the power is shut off. Since 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 issue is dealt with.

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 occurred further along in your home's electrical system. This could be the circuit breaker, fuse box or system switch. A knowledgeable technician will examine electrical connections and wiring until they uncover the source of the problem.

e294 - Critical

Critical error code e294 shows up 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 ensure it’s not simply a software issue. If that doesn’t work, they’ll examine the wiring diagram of the thermostat and begin inspecting connectors.

They’ll detach the power and slowly inspect each wire, making sure they are fully attached into the connector with the correct amount of bare copper. After they locate the malfunctioning connector, it can be exchanged for a new one.

e195 - Critical

This critical error code can appear when the weather outside is particularly 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 drains and the thermostat will subsequently power down. Presuming the breakers are on, you can inspect a few other places before contacting a professional technician.

As this error can consume your thermostat’s battery, the first step could be providing enough power to figure 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. In the event it reveals error code 195, you should continue to visually check components including 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 indicates an electrical issue with your Nest thermostat. More specifically, e103 can refer to an overcurrent problem, which means the wiring is receiving more power than necessary. This will sometimes stem from the breaker box, an error from the control board or because of a defective connection in the thermostat. A technician needs to meticulously examine and test the Nest’s electrical system to determine where the power is surging or why the thermostat thinks there’s an overcurrent problem.

n260

Although this error code isn’t critical, it can still stop you from using the Nest thermostat like normal. Error code n260 refers to the lack of a C wire or Nest Power Connector, as missing one can block your Nest from obtaining adequate power. You can check 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 may notice error code E297 be displayed. 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

Like error code e103, e104 is a critical error stemming from an overcurrent. If excessive power is sent through the Nest’s wiring, it may damage internal components and could 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 recommended to turn the power off as soon as possible. You can then get in touch with a professional technician with the necessary experience detecting and fixing electrical problems.

e73 - Critical

When your thermostat displays error code e73, it means that the Rc wire is not receiving power. This will sometimes be as straightforward as the breaker being switched off, but it can also be a problem with the wiring. After shutting off the power to your HVAC system and thermostat, you can visually check the wires to make sure nothing is loose or damaged. If nothing looks to be out of place, it’s time to contact a local professional.