In December two million Teslas were recalled due to a high-risk software flaw in the self-driving technology that could lead to crashes.

The flaw was uncovered after a two-year investigation by the National Highway Traffic Safety Administration

Tesla did not agree with the results of NHTSA’s investigation, as reported by the Associated Press.

Earlier this month, a safety group rated Tesla’s autopilot feature as “poor” for safety.

The Insurance Institute for Highway Safety said: “Some drivers may feel that partial automation makes long drives easier, but there is little evidence it makes driving safer.

“As many high-profile crashes have illustrated, it can introduce new risks when systems lack appropriate safeguards.”