Ford Motor is recalling 850,318 vehicles in the U.S. due to a potential low-pressure fuel pump failure, which could cause an engine stall, the U.S. National Highway Traffic Safety Administration said on Thursday.

Ford is recalling more than 850,000 of its cars across the U.S. because the low-pressure fuel pump inside the vehicles may fail — and potentially cause an engine stall while driving, increasing crash risks.

Ford said it began sending letters to affected owners this week to warn of safety risks related to potential fuel pump failures.