DEARBORN, Mich. – Ford Motor Co. voluntarily recalled more than 440,000 1997 Ford Escorts and Mercury Tracers on Wednesday to install a shield over the unit that monitors the air bag.

The world’s No. 2 automaker said fluid leaks or condensation could cause unintended air bag deployment, melted wiring, or fire. The problem was brought to Ford’s attention by the National Highway Traffic Safety Administration, but the company said very few incidents have been reported.

About 441,000 cars are affected worldwide; most are in the United States.