Volkswagen AG found "irregularities" in the stated carbon dioxide emissions and fuel consumption data of up to 800,000 Volkswagen, Audi, Skoda and Seat vehicles -- the latest issue in a now month-long emissions controversy that's hurt earnings and the stock price. The German carmaker said this one could cost 2 billion euros ($2.2 billion).

The new issue was discovered while investigating the first emissions issue, the company said. The cars involved in the carbon dioxide irregularities were sold in Europe, a company spokesman told BBC, which pointed out that carbon dioxide is a greenhouse gas, as opposed to the nitrogen oxide involved in earlier allegations, which is a pollutant that causes lung disease.

"During the course of internal investigations, irregularities were found when determining type approval CO2 levels," Volkswagen said in a statement. "Based on present knowledge around 800,000 vehicles from the Volkswagen Group could be affected. An initial estimate puts the economic risks at approximately two billion euros. The majority of the vehicles concerned have diesel engines."

“I have pushed hard for the relentless and comprehensive clarification of events," CEO Matthias Müller said in the statement. "We will stop at nothing and nobody. This is a painful process, but it is our only alternative. For us, the only thing that counts is the truth."

Müller took over last month after Martin Winterkorn resigned after the company admitted it installed software designed to cheat in emissions tests in up to 11 million vehicles. The company said it could cost 6.5 billion euros to fix those cars. Just yesterday, the company denied a new Environmental Protection Agency report that it installed the software in even more cars, including Porsche Cayennes.