VW'S top US executive learned of emissions issues in 2014
WASHINGTON (AP) -- 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 four-cylinder diesel cars.
But in prepared remarks posted Wednesday, 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.
Horn is scheduled to testify before the House Committee on Energy and Commerce Subcommittee on Oversight and Investigations, which was provided an advance copy of the executive's written testimony. It will be the first appearance on Capitol Hill by Horn, a German and veteran VW manager who took over the reins of the brand's American subsidiary last year.
SEE MORE: Dozens of deaths likely from VW pollution dodge
After the written version of Horn's remarks became public, Volkswagen spokeswoman Jeannine Ginivan told The Associated Press that Horn would testify on Thursday that he only learned of the cheating software "over the past several weeks."
In the written testimony, Horn echoes prior statements by the company's global CEO apologizing for the cheating, which hid illegal levels of pollution produced by nearly 500,000 "clean diesel" cars sold in the U.S. since 2008.
See photos related to the Volkswagen emissions scandal:
"On behalf of our company, and my colleagues in Germany, I would like to offer a sincere apology for Volkswagen's use of a software program that served to defeat the regular emissions testing regime," Horn will say, according to his prepared remarks. "These events are deeply troubling. I did not think that something like this was possible at the Volkswagen Group. We have broken the trust of our customers, dealerships, and employees, as well as the public and regulators."
Horn will also announce that VW is withdrawing applications seeking government emissions certifications for its 2016 model Jettas, Golfs, Passats and Beetles with diesel engines. The vehicles already shipped to the U.S. will remain quarantined in ports and dealers won't be able to sell them. That's a huge loss for VW dealers, who were hoping to put the new models on sale soon. For some, it's 30 percent of their business.
Following the delivery of his prepared remarks, Horn is expected to face a blistering round of follow-up questions from members of the committee.
"The American people want to know why these devices were in place, how the decision was made to install them and how they went undetected for so long," the panel's Republican chairman, Rep. Tim Murphy of Pennsylvania, said in a statement. "We will get them those answers."
Also scheduled to testify on Thursday are two officials at the Environmental Protection Agency who oversee emissions testing and compliance with clean air rules.
VW first confessed the deception to U.S. regulators on Sept. 3, more than a year after researchers at West Virginia University first published a study showing the real-world emissions of the company's Jetta and Passat models where far higher than allowed. The same cars had met emissions standards when tested in the lab.
VW was able to fool the EPA because the agency only tested the cars on treadmill-like devices called dynamometers and didn't use portable test equipment on real roads. The software in the cars' engine-control computers checked the speed, steering wheel position, air pressure and other factors to determine when dynamometer tests were under way. It then turned on pollution controls that reduced the output of nitrogen oxides that contribute to smog and other pollution, the EPA has said.
Only when the EPA and California regulators refused to approve VW's 2016 diesel models for sale did the company admit earlier what it had done. The company now faces billions in environmental fines, numerous class-action suits from angry customers, and a criminal investigation launched by EPA and the Justice Department.
Though VW and U.S. regulators have not yet announced a fix for illegal emissions under a nationwide recall, Horn will say the company is "determined to make things right."
"This includes accepting the consequences of our acts, providing a remedy, and beginning to restore the trust of our customers, dealerships, employees, the regulators, and the American public," Horn will say, according to his written testimony.
More from AOL.com:
Putin spends his birthday playing hockey with NHL stars
South Carolina still on edge from flooding; 2 people missing
Russia fires missiles as Syrian troops launch ground push