Ford is recalling about 1.4 million F-150 pickup trucks in the U.S. following a U.S. National Highway Traffic Safety Administration investigation into reports of unexpected downshifts, the regulator said on Friday.

The NHTSA said Ford was aware of two “potentially” related injuries and one accident, and that dealers would update the trucks’ powertrain control module software as a remedy.

Earlier this year, the regulator had expanded a safety-related investigation into the issue. A preliminary evaluation was first opened in March last year, after receiving complaints related to 2015–2017 F-150 pickups equipped with the ‘6R80’ transmission.

Ford had earlier said that the issue may have been caused by electrical connections wearing down over time due to heat and vibration, leading to signal loss from the transmission range sensor.

The regulator said that incorrect signals likely lead to an unintended downshift.

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(Reporting by Chandni Shah in Bengaluru; Editing by Mrigank Dhaniwala and Ronojoy Mazumdar)