BERLIN (AP) — Germany's Volkswagen, already reeling from news that it had cheated on U.S. tests for nitrogen oxide emissions, says an internal investigation has found new problems: "unexplained inconsistencies" in the carbon dioxide emissions from 800,000 vehicles.

The company warned Tuesday it estimated the possible "economic risks at approximately 2 billion euros" due to the new problem.

It did not identify which vehicles were affected, but said the flaw in no way compromised the safety of any of the vehicles.

The statement says the company will "will endeavor to clarify the further course of action as quickly as possible and ensure the correct CO2 classification for the vehicles affected" with the responsible authorities.