At the hearing, Mr. Horn is expected to apologize for the company’s trickery and to describe the steps it will take to investigate the episode, including finding remedies for the affected vehicles and adopting measures to prevent this from happening again.

Mr. Horn, in his prepared testimony, said Volkswagen was “working tirelessly to develop remedies for each of the affected groups of vehicles.” He explained that there were three groups of vehicles involved, each containing one of the three generations of the two-liter diesel engine, and that each would require a different solution. Volkswagen has indicated that it will fix its 11 million faulty diesel vehicles by the end of 2016.

As Volkswagen works with American officials to address the issues, Mr. Horn indicated that certain features on future models still needed regulatory approval. With that process incomplete, he said the company had withdrawn the application for certification of the 2016 model vehicles.

He also said that the company was examining its internal processes to make sure this kind of deception would not happen again. “Volkswagen knows that we will be judged not by words, but by our actions over the coming weeks and months,” said Mr. Horn.