Why Tesla Lights Sometimes Flash On Their Own When Parked

Have you ever been walking down the street and seen a parked Tesla car suddenly have its lights start flashing? It can be a little unnerving, especially when it’s late at night and there’s no one around obviously opening or accessing the car. When you see flashing lights you might first think someone is opening it up or activating it, but when you see that nobody is doing that, it can just feel plain strange!

In today’s blog, we’re looking in more detail at why it is sometimes that you might notice a parked Tesla’s lights flashing. There are several competing explanations, so we’ll try and see what seems the most likely.

Background: What’s the Issue of Tesla Flashing Lights?

Tesla Model Y parked up indoors with head lights on
Tesla Model Y parked up indoors with head lights on

As we mentioned in the introduction, since about 2018, there have been numerous reports and online discussions about a curious phenomenon where people walking by Teslas were greeted with flashing headlights.

Obviously, to many people this was fairly spooky and strange. The leading theory as to why it was happening came after the arrival of Tesla’s “Sentry Mode,” which we’ll cover in more detail in the next section.

The basic idea was that Sentry Mode was using the flashing lights as a warning to others when they “disturbed” the car in its sleep. When you remember that Sentry Mode as a real idea (and its apparently resulting flashing lights) had previously only been seen in shows like Knight Rider, it would be deeply troubling and disturbing to see lights flashing for no apparent reason.

It’s not like people at the time would immediately jump to the conclusion that it was this brand-new security system that none of them knew anything about.

The stories first emerged and sounded something like ghost stories; tales of unexplained paranormal activity. However, it wasn’t long before the more rational explanations started to emerge. We’ll cover some of those in the next section.

What Theories Exist to Explain This?

There are 3 main theories that are being used to explain the flashing lights when parked. After looking at each one, we’ll later think about which one seems to be the most likely.

Sentry Mode

First and foremost, people are explaining the flashing lights as part of the Tesla having its “Sentry Mode” activated. Tesla first started to install Sentry Mode on the 2017 models as an added security feature. By 2019, it had become a very advanced feature with a plethora of innovative and unique qualities designed to ward off would-be thieves.

Besides the flashing lights, Sentry Mode also lights up the central touchscreen with a glowing red eye which is very reminiscent of Hal 9000 from “2001: A Space Odyssey,” and also displays the word “Recording” to scare off anyone who might be trying to break in that they’re now on camera.

Other measures include playing music at full volume, sending alerts to Tesla owners on their app, and recording as much as it can of what is going on around the car to work as evidence in cases where hit and runs or vandalism has happened.

So, the lights flashing because of Sentry Mode is a fairly solid theory, but it only holds true for those who are very close to Tesla cars when it’s happening. If you were standing close to a Tesla admiring it and its Sentry Mode was active, then those security measures would also activate in case you happened to be a vandal or car thief.

If the phenomenon is indeed being caused by Sentry Mode, then the new “Stealth Mode” function should help to quieten that down and allow that system to work a bit more subtly.

Over-the-Air Updates

Tesla blog screenshot covering the new V11 software update
Tesla blog screenshot covering the new V11 software update

Another popular theory relates to various over-the-air (OTA) updates that Tesla cars receive, and in particular starting with an update received specifically on December 27, 20218. On that date, Tesla was rolling out a major software update called “2018.50.” It fixed various bugs and added several new features, and apparently the flashing lights was one of those new features.

The reason people believe this is the root of the problem is because there are no reports of it happening before the arrival of that 2018.50 update. The description of the issue was that at night time lights were going off, with the right one lighting up first, followed then by the left one.

Some were skeptical at first because it seemed unlikely that it would start happening across Tesla cars all at the same time from an update. Wouldn’t people be updating at different times, with many ignoring the update altogether like they might do a message from Windows Update?

Actually, no they wouldn’t. Tesla updates are more important than those on many other smart devices you own.

A smartphone system update might bring a few aesthetic changes and claim to “fix bugs” but the phone hardly ever works noticeably differently after each update. This is not the case with Tesla OTA updates. These updates make real and lasting changes to the car, adding features, fixing system bugs, but even helping to repair mechanical problems as it was discovered when reports came out of an OTA update that would reduce the braking distance on Tesla Model 3 cars by up to 20 feet or thereabouts.

So, could this 2018.50 update explain the arrival of the flashing lights feature? The OTA theory gets even more interesting when you consider the other side of it, which is that rather than an OTA update adding the flashing lights as a feature or some sort, the issue is that when a Tesla is connected to Wi-Fi, the latest OTA updates will start downloading and installing automatically. There are those who say that it’s during the update time that the car is just behaving awkwardly, and that’s why the lights flash. It’s just bugs within bugs.

The Weather

Another theory that exists is connected to the weather: cold weather to be precise. Drivers in cold climates such as the Colorado Rockies, and Alaska were noticing that their lights flashing at night, both when parked and sometimes while driving. These issues were reported both for Model S and Model 3 cars, and if you’ve experienced this, it’s recommended that you get it fixed at a Tesla service center immediately because obviously flashing headlights at night has certain safety implications.

Tesla service ahead sign outside a dealership in Germany
Tesla service ahead sign outside a dealership in Germany

Hacking?

One of the more paranoid and outlandish theories that also exists is to do with malicious groups and individuals hacking into Teslas to make their lights start flashing. We haven’t mentioned this as one of the 3 big theories because there’s too much to show that it’s most likely untrue.

Believers in this theory have said that the way that the right headlight flashes first, followed by the left one is some kind of deliberate code, perhaps Morse code spelling the initials of the hackers.

However, this doesn’t really fit with what’s been going on. When it comes to hacking, it would either be a hack into an individual car, which would mean only one car at a time would be doing it, but we know from users and witnesses that there are often multiple Tesla vehicles doing this at once. The only other possibility is that Tesla’s system is hacked, but that would most likely mean all Tesla vehicles would have their headlights flashing at the same time.

On top of that, Elon Musk already promised any would-be hacker a gift of a free Tesla Model 3 if they actually managed to hack into a Tesla car. Why wouldn’t the hackers be claiming their $45,000 prize?

Tesla and Artificial Intelligence

One more idea that people have posited that’s rather “out there” is the idea that Tesla cars with their fancy new AI-boosted features are starting to “wake up” and become self aware. They believe that our Teslas are being taken over by the robots within, a theory that is certainly exacerbated by the Hal 9000 red eye feature of Sentry Mode!

Elon Musk has quite forcefully denied such an idea, however, pointing out that the car only uses functional/targeted AI systems and that there isn’t some kind of huge central AI brain that controls everything and can start invading and taking over other systems of the car. 

Conclusion: No Need for Alarm; Take Action

Tesla headlight on close up shot
Tesla headlight on close up shot

If your own Tesla is experiencing issues with flashing lights, there’s no need to worry, because there are a few things you can do about it to stop it from happening. The first thing would be to turn off Sentry Mode unless you absolutely need it because you’re parked in a dodgy area for a while, for example.

The second thing to do would be to make sure you have updated to the latest software version. This one sounds a bit cliche as advice and you’ve probably heard it a million times from every smart product and software supplier when troubleshooting. In the case of Tesla cars, however, it really helps.
Finally, do your best to keep your Tesla out of extreme cold. If you can keep your Tesla in a garage, under a carport or in a cover, then that would also help in keeping the Tesla warm and stopping any extreme cold from creating various kinds of errors. It would also offer covering if the lights were still to go off in the night. At least when the car’s in the garage it won’t disturb anyone else in the neighborhood. It might give you a fright if you’re in the garage late at night looking for light bulbs, though!

About Tristan Perry

Tristan is a software developer who is passionate about eco-friendly lifestyles - and products, such as green cars! He has loved seeing Nissan and Tesla sell loads of quality EVs over the last decade - with every other car manufacturer finally following suit.

EV adoption seems to be at a tipping point now, with 'ordinary folk' starting to order them too. This is naturally aided by very expensive gas prices, but also a genuine desire for people to try and improve the environment.

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