A viral tweet showed a Tesla confusing the moon for a yellow traffic light.
The company's Full Self-Driving tech has made similar mistakes before.
Owners say their cars have been fooled by billboards and Burger King signs.
Tesla CEO Elon Musk has been promising for years now that fully autonomous vehicles are just over the horizon.
But his company's Full Self-Driving technology still doesn't live up to its name. And despite Musk's goal to eventually make the system safer than a human driver, it currently fails at things any human driver wouldn't think twice about.
For example, one Tesla owner posted a clip to Twitter on Thursday that showed his vehicle mistaking the moon for a traffic light over and over again as he cruised down the highway.
The clip shows a moon that's unusually yellow and low in the sky, so one can see why the car might register it as a yellow light and apply the brakes. Another owner replied with their own video showing the same scenario.
Still, the moon is a constant — not an extreme case — and it's something any self-driving system worth its salt should identify as being hundreds of thousands of miles away, not just up ahead. Plus, having a car slow down unexpectedly at highway speeds could create a dangerous situation for the driver and surrounding traffic.
To be fair, Tesla doesn't claim that Full Self-Driving can perfectly react to traffic lights and stop signs yet. The "Traffic Light and Stop Sign Control" feature, released via a software update in early 2020, is still in beta, and owners have to switch it on manually.
But it's not just the moon that's fooling Teslas. Owners have also reported their vehicles mistaking the sun for a red light. And one odd clip shows a Tesla get bamboozled by a truck hauling traffic lights.
In April, a Tesla owner noticed his car would always come to a full stop in the same spot in the middle of a road. A video he posted shows his vehicle mistaking an image of a stop sign on a billboard for the real thing.
Soon after Tesla launched the traffic light-sensing feature in April 2020, one Tesla owner posted a video of his car mistaking a roadside Burger King sign for a stop sign. The car begins to slow down on the 40-mph road before realizing there's no stop sign and carrying on.
Tesla solved the Burger King bug in a subsequent software update. Still, the fast food chain attempted to capitalize on the glitch by launching a free Whopper promotion for any Tesla owner whose car accidentally stopped at a Burger King sign.
In July, the carmaker launched a subscription option for Full Self-Driving, knocking its price from a $10,000 upfront payment to as little as $99 per month. But, as these bugs show, the system doesn't make cars autonomous and it's still not clear when it will.
In the meantime, it's arguably safer for Teslas to recognize too many traffic lights and stop signs than too few.