Tesla Inc. is under investigation by the United States National Highway Traffic Safety Administration after the agency found the automaker failed to report crashes as required.

Documents posted on NHTSA’s website on Thursday show that the agency’s Office of Defects Investigation identified multiple Tesla crash reports submitted months after the incidents occurred.

NHTSA said the delays were likely linked to a data collection issue, which Tesla has since addressed.

Under U.S. regulations, automakers must report collisions involving partially or fully automated driving systems on public roads within five days of becoming aware of the crash.

NHTSA said it will conduct an audit to determine whether Tesla complied with reporting requirements, assess the causes of delays, and review the measures the company has implemented to prevent future issues.

NHTSA will also examine whether Tesla failed to report any previous relevant collisions and whether the company’s submissions to the regulator “include all of the required and available data.”