The company said it will test employees who show symptoms but not all of its workers.
Ford was forced to halt its production on Wednesday after spotting a COVID-19 case at its assembly plant in Dearborn, Michigan, where the company produces the F-150 pickup truck.
On Tuesday, Ford also stopped production for a few hours at its Chicago plant, where the Ford Explorer, Lincoln Aviator, and Police Interceptor models are produced, after confirming that two employees at the facility had contracted the COVID-19.
The suspension of production comes just a few days after General Motors, Ford, and Fiat Chrysler (FCA) restarted production at most of their U.S. plants after eight weeks of closure.
Ford said that when an employee at the Dearborn truck plant tested positive for COVID-19, they immediately began notifying people who were in close contact with the infected worker to ask them to isolate themselves.
The company implemented the same protocol after detecting two COVID-19 cases on Tuesday at the Chicago plant, where some 5,810 people work.
Among the actions aimed at preventing COVID-19 outbreaks, Ford included taking the temperature of those who enter its factories. However, its latest COVID-19 cases were not detected when entering the facilities and the disease was confirmed after testing employees.
The U.S.-based company said it will test employees who show symptoms but not all of its workers.
On Thursday, U.S. President Donald Trump is expected to visit the Ford plant in Rawsonville, Michigan, where the company has been producing thousands of respirators in recent weeks.