The Environmental Protection Agency (EPA) has accused the German automaker of selling about 482,000 vehicles since 2008 that violate the Clean Air Act due to software installed on the vehicles that activates required air pollution protections only during emissions tests.
Horn's expected resignation follows the departure of Volkswagen Group CEO Martin Winterkorn as the German automaker scrambles to contain the fallout from the emission scandal.
Volkswagen has been embroiled in scandal since the EPA revealed last Friday that the company programmed vehicles to trick emissions testers into believing that its diesel cars released a much lower volume of nitrogen oxide than they actually do.
A “defeat device” in the vehicles made it so that they would pass emissions tests. But in regular driving, they emitted up to 40-times more pollution.
Volkswagen has admitted to the accusations.
The EPA has said Volkswagen could face up to an $18 billion fine for its pollution violations.
— Timothy Cama contributed to this report.