Germany's Volkswagen, already reeling from news that it had cheated on US 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," or about USD 2.2 billion, 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.

As a result of the new emissions revelation, Volkswagen's main shareholder Porsche SE, issued a profit warning, saying that the group now expects a total profit for the fiscal year 2015 between 0.8 billion euros and 1.8 billion euros.

In a press release, Porche SE stated that its forecast is subject to estimation risks because it is based on the assumption that Volkswagen's year-end results will be within the range of previous expectations.

Additionally, the shareholder group's expected net liquidity has decreased, and it is now expecting a net liquidity between 1.3 billion euros and 1.5 billion euros by year end.

Volkswagen's 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.

In a related matter, Porsche Cars North America announced on Tuesday a plan to voluntarily halt sales of the cars affected by new claims made by the EPA. The Atlanta-based company, which holds exclusive rights to import certain models, will stop selling model years 2014-2016 of the Porsche Cayenne Diesel vehicles until further notice.

First Published:Nov 4, 2015 8:05 AM IST