Ford Motor said Tuesday it is recalling 668,000 F-150 pickup trucks worldwide from the 2014 model year because vehicles can unexpectedly downshift into the first gear causing a loss of driver control or rear-wheel lockup.

A loss of signal can cause a transmission downshift, regardless of vehicle speed, the company told the National Highway Traffic Safety Administration. Dealers will update the powertrain control module software in the trucks.

The Ford F-series pickup truck has been the best selling vehicle in the United States for more than 40 years.

This is the latest recall by the automaker over the issue since 2016 and comes after NHTSA in March opened an investigation into whether 2014 model trucks needed to be recalled after receiving complaints about trucks unexpectedly downshifting without warning.

The new recall covers 552,000 vehicles in the United States. Ford said it is aware of 300 warranty reports, 96 field reports and 124 customer complaints covering 482 vehicles related to unexpected transmission downshifting on 2014 F-150

vehicles, including two injury reports and one crash that may be related to the recall issue.

NHTSA said one owner said he “experienced an

unexpected downshift causing his vehicle to crash into a concrete barrier and another vehicle, injuring both

him and the driver of the other vehicle.”

Ford in 2016 recalled 153,000 2011-2012 Ford F-150 vehicles equipped with six-speed automatic transmissions to address the downshift issue.

NHTSA opened a probe into the issue in December 2017 and in February 2019 Ford expanded its recall to cover 1.48 million F-150 trucks in North America, including 2013 models.

Later in 2019, Ford issued a recall for 107,000 2013 F-150 vehicles due to an issue with the fix.

Since March of this year, Ford and NHTSA have met on several occasions to discuss the issue before Ford agreed to the latest recall but Ford said the rate of unexpected downshift reports remains lower for 2014 vehicles than the 2011-2013 F-150 vehicles previously recalled.

(Reporting by David Shepardson in Washington Gursimran Kaur and Shivansh Tiwary in Bengaluru; editing by Mrigank Dhaniwala and Jason Neely)