But according to the internal inquiry, the engines proved unable to live up to that standard and meet air-quality emissions standards. Volkswagen’s big bet on the future was poised to fail.

It was not yet clear how many countries’ emissions standards the new motor would have been able to meet without cheating. But the United States, with its limits on diesel emissions that are much stricter than those of the European Union, was one of the most important.

Cars from the 2009 model year were the first to arrive in the United States with the new motors. By that point, it would have been a severe setback to cancel production and go back to the drawing board.

It remained unclear who made the decision to solve the emissions problem by installing software deliberately devised to cheat on emissions tests. The software could recognize when a car was undergoing emissions tests and set temporary pollution controls so that the vehicle would pass. During normal operation, the cars could emit as much as 40 times the allowed amount of nitrogen oxides, a class of harmful pollutants.

The recently suspended managers were all people in central decision-making roles. They are Ulrich Hackenberg, head of development for all Volkswagen Group brands, and previously head of development for Volkswagen-brand cars from 2007 to 2013; Heinz-Jakob Neusser, currently head of development for the Volkswagen brand; and Wolfgang Hatz, head of engines and transmissions development for all Volkswagen brands.

The three suspended executives could not be reached for comment.

A few years before discovering that the EA 189 engines could not satisfy pollution regulations, Volkswagen made a fateful decision not to use a more expensive diesel-emissions technology developed jointly with its rival Daimler, the maker of Mercedes-Benz cars. Instead, in 2007 Volkswagen announced that it would use its own method for controlling emissions of nitrogen oxides and other harmful pollutants. That system, when used on the EA 189 engines, proved inadequate for the task.