DETROIT >> The federal government is closing an investigation into 1.6 million Ford vehicles that can lose engine power after Ford agreed to a remedy.

The yearlong investigation involves Ford Escape and Mercury Mariner SUVs and Ford Fusion and Mercury Milan sedans from the 2009 through 2013 model years.

Vehicles with 2.5-liter and 3.0-liter engines can suddenly lose power because of material buildup in the electronic throttle body motor. The engines don’t stall, but vehicle speeds can drop as low as 5 miles per hour.

Ford and the National Highway Traffic Safety Administration have received nearly 12,000 complaints about the issue. There have been three reported accidents and one reported injury related to the problem.

Ford spokeswoman Kelli Felker said Tuesday that new software won’t fix the problem, but it will allow affected vehicles to travel at least 40 miles per hour in what is known as “limp home mode.” Ford also extended the warranty on the electronic throttle bodies to 10 years or 150,000 miles.

Dealers will update the software and clean the electronic throttle bodies for free. Ford began notifying customers in January.