And as the year began, the company’s toughest problems seemed to be in the past. After initial production troubles with the Model 3, its assembly line in Fremont, Calif., was churning out the new sedan, and customers were flocking to its stores. It reported profits for both the third and fourth quarters of 2018. Mr. Musk felt confident enough to predict the company would remain profitable “every quarter going forward.”

But its business has gotten off track. On Jan. 1, the federal tax credit available to Tesla customers fell to $3,750 from $7,500. That effectively increased the cost of its cars and caused sales to slow in the United States. Sales of the Model 3 in Europe and China got off to a bumpy start. After laying off 7 percent of its work force, Tesla reported a first-quarter loss of $702 million. The company expects to lose money again in the second quarter.

The recent concerns go beyond Tesla’s bottom line. Its Autopilot driver-assistance system has come under renewed scrutiny after a Model 3 hit a tractor-trailer in Florida, killing the driver. Autopilot was operating, and neither it nor the driver activated the brakes. Tesla has acknowledged that Autopilot cannot recognize all objects and may not brake for stationary vehicles.

Still, the company said the system significantly reduced the likelihood of crashes. In the first quarter of the year, Tesla drivers using Autopilot had one accident for every 2.87 million miles driven, the company said, while data from federal safety regulators shows that the national average for all vehicles is one every 436,000 miles.

In a May review of the latest version of Autopilot, which can navigate to a specific destination and change lanes without prompting by a human driver, Consumer Reports found that the system operated erratically and sometimes cut off other cars.

“It was like a first-time driver that was nearsighted,” said Jake Fisher, the magazine’s director of auto testing. Consumer Reports had earlier removed its “recommended” rating from the Model 3, citing “declining reliability.”