FRANKFURT, Germany (AP) — The former head of Volkswagen's luxury division Audi pleaded guilty Tuesday to charges tied to the automaker's diesel emissions scandal, becoming the highest-ranking executive convicted over cars that cheated on emissions tests with the help of illegal software.

Rupert Stadler answered "yes" to a statement read in court by his attorney that said Stadler admitted wrongdoing and regret for his failure to keep rigged cars off the market even after the scandal had become public knowledge, the dpa news agency reported.

Stadler entered the plea under an agreement with the judge and prosecutors that provides probation instead of jail time and orders him to pay a 1.1 million euro ($1.2 million) fine in return for a thorough admission of guilt.

Three lower-ranking managers also have taken plea deals in the 2 1/2-year-long trial in Munich.

Stadler had been charged with fraud and false certification by prosecutors who said he let cars with rigged software be sold after September 2015. That's when the U.S. Environmental Protection Agency issued a notice of violation under the Clean Air Act after discovering the rigged software.

The software turned on emission controls when the cars were on test stands and turned them off when the cars were on the road. The cars would pass inspection but emitted many times the permitted level of nitrogen oxide, a pollutant that can harm people's health.

The scandal cost Volkswagen more than $30 billion in fines and settlements and saw two U.S. executives sent to prison.

It pushed the entire auto industry away from reliance on diesel engines, which had been almost half the auto market in Europe, and helped accelerate the push into electric vehicles.

Volkswagen has since become one of the world's biggest makers of battery-only cars.

Former VW CEO Martin Winterkorn, who resigned in the wake of the 2015 EPA announcement, has been charged by U.S. and German authorities, but Germany does not generally extradite its citizens to countries outside the European Union. German proceedings against him also have stalled because he is in poor health.