Tesla built a network of connected cars. What happens when it goes down?

The outage, however, provided a glimpse into some of the real-world issues created by the evolution of increasingly connected vehicles that rely on the Internet. Telsa vehicles use mobile connections for a wide range of functions, including remotely setting heating and air conditioning and making service appointments. They also unlock the features of vehicles’ Autopilot driver-assistance system, which can navigate highways and city streets between waypoints set by the driver. A feature to summon a vehicle in a crowded parking lot, for example, was inaccessible because it is accessed through the app.

“It’s like what you see in a lot of other areas of our lives,” said Karl Brauer, a veteran auto industry analyst who works as an executive analyst at the website iSeeCars. “When we get this increased convenience, we tend to become a lot more expectant and dependent on it.”

On social media, users reported a range of services being down, including being unable to get into their cars. Typically, they can unlock their doors and start their vehicles by pressing icons in the company’s mobile app. Tesla issues physical key cards to unlock cars as a backup.

Phones should normally pair with the cars via Bluetooth to unlock the doors, a connection the network outage would not disrupt. But some users said they had trouble logging into the app at all.

Tesla encourages owners to pair their cars with their phones but says they should carry backups.

“Tesla recommends that you always have a functional physical key readily available if parking in an area with limited or absent cellular service, such as an indoor parking garage,” the company says on its website.

Connected cars will likely only become more prevalent in society as the auto industry embarks on a shift to electrification prompted by environmental goals and the growing impacts of climate change. California Gov. Gavin Newsom (D) on Wednesday announced the state would stop the sale of gasoline-powered cars by 2035, a target that could usher in a sea change toward electric vehicles, which are loaded with sensors and battery-powered components connected to the Internet.

But as Wednesday’s outage highlighted, that transition won’t always be smooth.

One user on Twitter asked Tesla whether the app was down early Wednesday morning because he had run into car trouble.

“I have a flat tire and can’t access my app to request roadside assistance,” the user wrote.

The website Electrek was first to report on what it called a “complete network outage.”

Tesla did not respond to a request for comment on the nature or scope of the outages.