Federal auto safety regulators are investigating why Tesla has repeatedly broken rules requiring it to quickly tell them about crashes involving its self-driving technology, a potentially significant development given the company’s plans to put hundreds of thousands of driverless cars on U.S. roads over the next year.

The National Highway Traffic Safety Administration is investigating Tesla, alleging it is failing to report crashes in a timely manner.

The road safety regulator said in a notice that Tesla submitted crash data that involves its driver assistance systems months after the incident.