WASHINGTON, March 9 (Reuters) - Volkswagen AG's top U.S. executive is stepping down nearly six months after the German automaker admitted to installing software to allow 580,000 diesel U.S. vehicles to emit excess emissions, the company said on Wednesday.
Michael Horn, who has been president and chief executive officer of Volkswagen of America since 2014, is leaving by mutual agreement "to pursue other opportunities effective immediately," VW said.
Horn could not immediately be reached. A lawyer for Horn did not immediately return a call seeking comment.
The German automaker said on an interim basis, Hinrich J. Woebcken, who was recently named the new head of the North American Region and chairman of Volkswagen Group of America, will assume Horn's role.
See images from the emissions scandal:
Volkswagen emissions scandal
Volkswagen's top US executive is stepping down immediately
The Oct. 5, 2015 photo shows a man sitting on a bench in front of the Volkswagen factories in Wolfsburg, northern Germany. For Volkswagen, the cost of its cheating on emissions tests in the U.S. is likely to run into the tens of billions of dollars and prematurely end its long-sought status as the world's biggest carmaker. (Julian Stratenschulte/dpa via AP)
FILE - In this Sept. 21, 2015 file photo President and CEO of Volkswagen Group of America, Inc. Michael Horn at the Brooklyn Navy Yard in New York. Volkswagen's top U.S.-based executive is expected to testify before Congress Thursday that he first learned in 2014 of emissions problems with the German automaker's diesel cars. But in prepared remarks, Volkswagen Group of America CEO Michael Horn doesn't directly address when he was first told his company had developed on-board computer software designed to deceive emissions tests. (AP Photo/Kevin Hagen, File)
Hans Dieter Poetsch, new chairman of the board of directors of the Volkswagen stock company, arrives for a press statement at the company headquarter in Wolfsburg, Germany, Wednesday, Oct. 7, 2015. He fills a position vacated when longtime chairman Ferdinand Piech resigned in April. (AP Photo/Michael Sohn)
This photo taken on Sept. 29, 2015 shows the power plant of the Volkswagen factory in the city Wolfsburg, Germany. Thanks to Volkswagen, Wolfsburg boomed in West Germanyâs postwar rebirth and today the town and the company are inseparable. (AP Photo/Markus Schreiber)
This photo taken on Sept. 29, 2015 shows the power plant of the Volkswagen factory and the Science Center, right, in the city Wolfsburg, Germany. Thanks to Volkswagen, Wolfsburg boomed in West Germanyâs postwar rebirth and today the town and the company are inseparable. (AP Photo/Markus Schreiber)
In this Sept. 30, 2015, photo, John Swanton, spokesman with the California Air Resources Board explains how a 2013 Volkswagen Passat with a diesel engine is evaluated at the emissions test lab in El Monte, Calif. Three years after Volkswagen opened a pollution testing center in Oxnard, Calif., VW admitted that it manipulated emissions results in 482,000 U.S. diesel vehicles to make them appear to run cleaner, raising questions around Volkswagenâs only test center in North America. (AP Photo/Nick Ut)
New cars of the German car manufacturer Volkswagen are ready to be shipped at the Volkswagen factory in Emden, Germany, Sept. 30, 2015. (Ingo Wagner, dpa via AP)
This Sept. 28, 2015 photo shows Volkswagenâs only test center in North America in Oxnard, Calif. Three years after Volkswagen opened the pollution testing center, VW admitted that it manipulated emissions results in 482,000 U.S. diesel vehicles to make them appear to run cleaner, raising questions around Volkswagenâs only test center in North America. (AP Photo/Gillian Flaccus)
Newly appointed Volkswagen CEO Matthias Mueller smiles during a press statement after a meeting of Volkswagen's supervisory board in Wolfsburg, Germany, Friday, Sept. 25, 2015, after CEO Martin Winterkorn resigned on Wednesday amid an emissions scandal. (AP Photo/Michael Sohn)
RETRANSMITS graphic that moved Oct. 3; graphic shows vehicles affected by Volkswagen's emissions violations and estimated deaths in the U.S. from the excess pollution; 3c x 5 inches; 146 mm x 127 mm;
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Horn's departure comes as VW continues to negotiate with California, the Justice Department and Environmental Protection Agency on possible fixes or buybacks for the diesel vehicles. It faces a March 24 deadline to tell a federal judge whether it has an acceptable fix.
A top California official told state lawmakers Tuesday that VW may only be able to mount a partial fix and may have to pay to mitigate the harm caused by allowing vehicles to remain on the road.
During the initial response to the crisis, Horn was VW's public face in the United States, apologizing days after the scandal became public and testifying before Congress.
"Let's be clear about this: our company was dishonest - with the EPA and the California Air Resources Board - and with all of you. And in my German words: We totally screwed up. We must fix those cars," Horn said in New York on Sept. 21.
In October, Horn told a U.S. House of Representatives panel that VW's supervisory board and top leadership did not intentionally order the cheating, but said it was the work of a few individuals. Asked by Rep. Joe Barton, a Republican from Texas, if it made sense that a company like VW could allow a fraud to go on for seven years without top leaders knowing, Horn was blunt.
"I agree it is very hard to believe," he said. "Some people made the wrong decisions."
Horn told Congress he had no knowledge of the cheating.
He became CEO based at VW's U.S. headquarters in Herndon, Virginia following the resignation of his predecessor, Jonathan Browning who abruptly resigned after VW brand sales fell in 2013. Sales fell despite an aggressive plan announced in 2008 by VW to triple sales in 10 years. (Reporting by David Shepardson; Editing by Chris Reese and Alistair Bell)