The US head of Volkswagen admitted he knew about the emissions cheating in spring last year.
In a statement released ahead of his hearing with the House Committee on Energy and Commerce today, Michael Horn said he was told there was a “possible emissions non-compliance” in 2014.
The company however did not tell US authorities about the situation until September this year.
Volkswagen revealed 11 million vehicles have been fitted with the so-called “defeat devices” but pose no threat to vehicle safety. They however exceed the legal limit of nitrogen oxides which are toxic to humans.
Mr Horn added: “I was informed that EPA [Environmental Protection Agency] regulations included various penalties for non-compliance with the emissions standards and that the agencies can conduct engineering tests which could include defeat device testing or analysis.
“I was also informed that the company engineers would work with the agencies to resolve the issue. Later in 2014, I was informed that the technical teams had a specific plan for remedies to bring the vehicles into compliance and that they were engaged with the agencies about the process.”
He added the company is taking full responsibility for its actions and co-operating with all relevant authorities.
Mr Horn went on: “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.”
Last month Volkswagen CEO Martin Winterkorn resigned after the firm admitted falsifying emissions.