Volkswagen CEO Martin Winterkorn resigned on Tuesday as the company grapples with an emissions cheating scandal, though he denied any personal wrongdoing.

“I am shocked by the events of the past few days. Above all, I am stunned that misconduct on such a scale was possible in the Volkswagen Group,” Winterkorn said in a statement.

“As CEO I accept responsibility for the irregularities that have been found in diesel engines and have therefore requested the Supervisory Board to agree on terminating my function as CEO of the Volkswagen Group. I am doing this in the interests of the company even though I am not aware of any wrong doing on my part.”

A subcommittee of the company’s board was meeting Wednesday to decide whether to recommend an extension of the CEO’s contract, which was coincidentally up for renewal this week.

“Volkswagen needs a fresh start — also in terms of personnel. I am clearing the way for this fresh start with my resignation,” Winterkorn said. “I have always been driven by my desire to serve this company, especially our customers and employees. Volkswagen has been, is and will always be my life.”

Volkswagen’s board is expected to appoint a new CEO when its full board meets Friday.

“The process of clarification and transparency must continue. This is the only way to win back trust. I am convinced that the Volkswagen Group and its team will overcome this grave crisis.”

Volkswagen is already the subject of several probes, including an criminal investigation in the U.S.

There’s no proof that Winterkorn knew about the “defeat device,” which the Environmental Protection Agency disclosed on Friday.

But an examination of the automaker’s past embellishments of its diesel technology could prove damaging to the company’s executive team, perhaps including Winterkorn.

One October 2008 company release bragged that Volkswagen engineers had slashed nitrogen oxide emissions by up to 90 percent by making “modifications within the engine.”

The company also boasted in an annual report of its regular environmental audits, telling investors that it ensures the company is meeting certifications by repeatedly examining its technology and emissions processes.

A Volkswagen spokesman has not responded to a request about whether Winterkorn knew about these statements.

The emissions scandal has crushed Volkswagen shares, spawned government investigations and lawsuits, called the future of diesel vehicles into question and raised questions about Winterkorn’s knowledge of the situation.

It is well documented within the industry that Winterkorn has not betrayed an emphasis on details despite a lust for global growth.

Several years ago he mapped out a goal to make Volkswagen the world’s largest automaker — a title it seized from Toyota in the first six months of 2015, but which now appears unlikely to retain for the full year.

But Winterkorn has long retained control over engineering details that many other CEOs would relinquish fully to deputies.

Whether that extended to knowledge of the sophisticated software installed in Volkswagen cars to deceive regulators is unclear.

“This is not a mistake that this software was on vehicles. There was intent,” said Dave Sullivan, an AutoPacific analyst, in an interview Tuesday. “I don’t think there was any excuse for something like this.”

Winterkorn, 68, led Volkswagen since 2007. He studied metallurgy and metal physics at the University of Stuttgart and then earned his doctorate in 1977 from the Max-Planck-Institute for Metal Research. He held several roles in quality assurance for Volkswagen and one of its luxury brands, Audi, before ascending to top executive roles.

On Tuesday, Winterkorn apologized for the company’s transgression and pledged to regain the public’s trust. He ordered an external investigation in addition to the Environmental Protection Agency’s investigation, a U.S. Justice Department criminal investigation and other probes expected in Europe.

“At present we do not yet have all the answers to all the questions,” he said at the time. “But we are working hard to find out exactly what happened. To do that, we are putting everything on the table, as quickly, thoroughly and transparently as possible.”

In the U.S., the deceptive software affects the four-cylinder diesel versions of the 2009 to 2015 Jetta, Beetle and Golf; the 2014 and 2015 Passat; and the 2009 to 2015 Audi A3.

Particularly problematic for Volkswagen, if not Winterkorn himself, is the company’s consistent bragging about its “clean diesel” technology and environmental sustainability.

In the company’s 2009 annual report, for example, it boasts that “environmentally oriented management is one of the keystones of our corporate culture” and says its environmental policy involves an effort “to continuously improve the environmental compatability of our products over their entire life cycle.”

It added: “All environmental management systems are regularly reviewed and optimized in regular internal and external environmental audits.”

In an October 2008 press release, Volkswagen crowed about one of the vehicles now known to have been fitted with deceptive software designed to mask the emission of nitrogen oxides, which are released at rates of up to 40 times acceptable standards.

The Jetta diesel car, Volkswagen said in the release, earned praise from the EPA for its “excellent consumption figures” and meeting “stringent California emission standards” by leveraging an exhaust treatment system powered by a nitrogen oxide storage catalytic converter.

“This was achieved through modifications within the engine and by implementing an exhaust treatment system developed especially by Volkswagen and which reduces nitrogen oxide emissions (NOx) by up to 90 percent,” Volkswagen said in the news release. “The central element of the exhaust treatment system is the NOx storage catalytic converter.”

Winterkorn’s position in the Volkswagen hierarchy was already teetering this summer. Several months ago, the company’s then-chairman Ferdinand Piech tried to displace Winterkorn, but was himself ousted.

But Piech, whose family controls more than half of Volkswagen shares along with the Porsche family, retains strong influence in the company’s affairs.

Consequently, Winterkorn was not awarded the chairmanship — a title that went to the automaker’s chief financial officer, Hans-Dieter Potsche, in a move that signaled a lack of complete confidence in Winterkorn’s reign.

Follow USA TODAY reporter Nathan Bomey on Twitter @NathanBomey.