DETROIT (AP) — The U.S. government’s auto safety agency is investigating whether last year’s recall of Tesla’s Autopilot driving system did enough to make sure drivers pay attention to the road.

The National Highway Traffic Safety Administration says in documents posted on its website Friday that Tesla has reported 20 more crashes involving Autopilot and since the recall. The crashes and agency tests raised concerns about the effectiveness of the remedy. The recall involved more than 2 million vehicles, nearly all the vehicles that Tesla had sold at the time.

The agency pushed the company to do the recall after a two-year investigation into Autopilot’s driver monitoring system, which measures torque on the steering wheel from a driver’s hands. In the probe, the agency was looking at multiple cases in which Teslas on Autopilot ran into emergency vehicles parked on freeways.