Ever had your thermostat suddenly stop working on a hot day, flashing something like “E298” and leaving you sweating in confusion? That’s not just a random string of letters and numbers. It’s a code, and it usually means your Google Nest thermostat isn’t getting the power it needs. This happens more often than you might think and can throw off your whole day—especially if the heat or AC shuts off. So what’s really going on with this error?
It means your Nest lost power
If your Nest thermostat shows E298, it’s basically saying, “Hey, I can’t get any power!” Just like your phone won’t work with a dead battery, your thermostat needs power to do its job. This usually happens when there’s an issue with the R wire, which is the main power line for the Nest. Without that, the screen might go black or flash that dreaded E298 message.
This can be scary, but you’re not alone. Tons of people deal with this—especially after installing a new system or during super hot days. According to the Google Nest forum, this is one of the most common complaints from users. Sometimes it’s just a loose wire, but other times it’s something deeper.
Wiring problems are a big cause
One of the top reasons you’ll see the E298 error is because of a wiring issue. Maybe a wire got knocked loose during installation, or maybe it wasn’t fully pushed into its slot. Even if everything looks okay at first glance, wires can shift or come undone over time. Nest is picky—every wire has to be just right or it’ll act up.
If you just installed your thermostat or had someone working on your HVAC, double check the wiring. Pull off the Nest display and take a peek. The R wire especially should be snug. Google even recommends checking the power connector or adding a C wire if the issue keeps coming back.
Sometimes it’s your HVAC’s safety shutoff
Believe it or not, your AC might be doing its job too well. Some air conditioners come with a built-in safety switch. If water starts to back up in the drain line or the system overheats, it’ll shut down the power. That’s great for protecting the unit—but not so great when it takes your thermostat offline, too.
One Reddit user shared how their drain line had a small clog. The backup water tripped a sensor and cut power to the whole system, causing the E298 error. The power came and went as the water evaporated, which made the issue even more confusing. So, if your Nest keeps going off and on, it might not be broken—it might be your AC trying to protect itself.
Resetting might be a temporary fix
When electronics misbehave, what’s the first thing we do? Turn it off and back on, of course. The same thing can sometimes work with a Nest thermostat. If you’re seeing E298, restarting the system might clear it—at least for a little while. It’s not a permanent fix, but it might help you cool down until you can check the wiring or call for help.
One user said flipping their HVAC breaker off and on made the error go away for a bit. You can also try rebooting the thermostat itself. Hold the ring down for about 10 seconds until it restarts. But if the error keeps coming back, it’s time to investigate deeper.
When to check the fuse or breaker
If your thermostat goes completely dead and shows E298, you might think it’s the device itself. But sometimes the real issue is hiding in your breaker box or your HVAC unit’s fuse. A blown fuse or tripped breaker can stop the power from ever reaching your Nest. It’s an easy thing to overlook if you’re not used to poking around in those areas.
The HVAC fuse can blow if something causes an electrical short or overload. If the breaker is off or the fuse is dead, your Nest won’t have a chance. A quick check of your breaker and a visual look at the fuse could save you hours of frustration.
Your system might need a C wire
Older heating and cooling systems don’t always have a C wire (short for “common wire”). That’s the wire that keeps your thermostat powered all the time. Without it, the Nest has to rely on other wires that weren’t really meant for that job. That’s when power issues like E298 tend to show up.
If your system is missing a C wire, you can usually fix that by adding a Nest Power Connector. It’s a small device that adds that missing wire without needing to run new wiring through your walls. According to troubleshooting guides, this solves power issues in a lot of homes that have older wiring setups.
Professional help might be your best bet
If you’ve checked the wiring, restarted the system, flipped the breakers, and it still shows E298—yeah, it’s time to call someone. An HVAC technician can test for problems you can’t see, like internal wiring issues or broken parts inside the furnace or AC unit. Sometimes the issue is behind a panel you shouldn’t open yourself.
The good news? Fixing an error like this usually doesn’t cost a fortune. Most repairs fall between $75 and $200. That’s for parts and labor. And once it’s fixed, you can finally go back to letting your Nest do its thing without interruptions.
It’s not always the Nest’s fault
It’s easy to blame the Nest itself when things go wrong. After all, that’s what you see blinking with an error. But in most cases, it’s just the messenger. The real problem is usually somewhere else—like the wiring, the AC unit, or a fuse. Replacing the thermostat won’t help if the system behind it isn’t working right.
Plenty of users have reported getting frustrated, only to find out their Nest was perfectly fine. It just wasn’t getting power. So before tossing it or returning it, make sure to run through the basic checks and maybe even contact support to walk through your setup.
When your thermostat shows Error E298, it can feel like a mystery you didn’t sign up for. But now you know—it’s all about power. Whether it’s a wire, a fuse, or a clogged drain, the Nest is just trying to keep you in the loop. Don’t panic. A few simple checks might get everything humming again in no time.