Tesla is recalling more than two million vehicles in the US to install new safeguards in its Autopilot advanced driver-assistance system, after a federal safety regulator cited safety concerns.

The largest-ever Tesla recall appears to cover nearly all vehicles on US roads to better ensure drivers pay attention when using the system.

Tesla’s recall filing said that Autopilot’s software system controls “may not be sufficient to prevent driver misuse” and could increase the risk of a crash.

The National Highway Traffic Safety Administration (NHTSA) has spent more than two years investigating whether vehicles produced by the electric auto maker led by billionaire Elon Musk adequately ensure drivers pay attention.

Acting NHTSA administrator Ann Carlson praised Tesla for agreeing to the recall.

“One of the things we determined is that drivers are not always paying attention when that system is on,” she said at a US House hearing.

Carlson said the agency opened a safety probe in August 2021 when she kept hearing about fatal crashes involving use of Autopilot.

Separately, Transport Canada said Tesla would recall 193,000 vehicles to address the Autopilot issue. It was not immediately clear if China will demand a recall.

Tesla’s Autopilot is intended to enable cars to steer, accelerate and brake automatically within their lane, while enhanced Autopilot can assist in changing lanes on highways but does not make vehicles autonomous.

One component of Autopilot is Autosteer, which maintains a set speed or following distance and works to keep a vehicle in its driving lane.

Tesla said it did not agree with NHTSA’s analysis but would deploy an over-the-air software update that would “incorporate additional controls and alerts to those already existing on affected vehicles to further encourage the driver to adhere to their continuous driving responsibility whenever Autosteer is engaged”.

US senators Ed Markey and Richard Blumenthal said the recall  was needed but “egregiously overdue … We urge NHTSA to continue its investigations to spur necessary recalls, and Tesla to stop misleading drivers and putting the public in great danger.”

NHTSA said its investigation into Autopilot would remain open as it monitors Tesla’s remedies.

Tesla did not respond to a question on the extent of the recall worldwide.

NHTSA opened its August 2021 probe of Autopilot after identifying more than a dozen crashes in which Tesla vehicles hit stationary emergency vehicles.

It found Autopilot “can provide inadequate driver engagement and usage controls that can lead to foreseeable misuse”.

NHTSA reviewed 956 crashes where Autopilot was initially alleged to have been in use and focused on 322 Autopilot-involved crashes.

Tesla will roll out the update to 2.03 million Model S, X, 3 and Y vehicles in the US dating to 2012, the agency said.

Tesla disclosed in October the US Justice Department issued subpoenas related to its Full Self-Driving and Autopilot.

Tesla in February recalled 362,000 US vehicles to update its FSD Beta software after NHTSA said the vehicles did not adequately adhere to traffic safety laws and could cause crashes.

– AAP