Ford NYSE:F is recalling about 741K vehicles over a transmission defect that could allow some vehicles to roll while parked.

The recall covers 2018 and 2021 Lincoln Navigator and Ford Expedition SUVs, 2020 and 2021 Ford Explorer and Lincoln Aviator models, and 2021 F-150 pickups. Ford will replace damaged transmission parts and update vehicle software at no cost to owners.

The company is also recalling more than 30K Bronco SUVs because improperly secured fender flares could detach and create road hazards.

The recalls add to Ford's quality-control challenge. The company has already issued more than 40 recalls this year, the most among domestic automakers. Still, Ford has been trying to improve defect detection by leaning on veteran engineers and AI tools.