The US Environmental Protection Agency (EPA) has requested information from Daimler’s Mercedes-Benz to explain emissions levels in some of its cars, the automaker conformed.

A Daimler spokesman told Reuters the automaker was fully cooperating with the request for information, and that Mercedes-Benz cars conformed with all rules and norms.

Daimler said the EPA request came in response to a class-action lawsuit filed by law firm Hagens Berman on 18 February, 2016, in US District Court for the District of New Jersey, accusing Mercedes of deceiving consumers with false representations of its BlueTEC vehicles, which it marketed as “the world’s cleanest and most advanced diesel”.

A Daimler spokesman told Reuters the suit was wholly unfounded and without merit.

The lawsuit alleges the automaker knowingly programmed its Clean Diesel vehicles to emit illegal, dangerous levels of nitrogen oxide, or NOx, at levels 65 times higher than those permitted by the EPA when operating in temperatures below 50 degrees F (10 C).

But Daimler said its cars conformed to all relevant rules and regulations.

It said, however, that under certain circumstances, a system to treat exhaust fumes could operate at a level of reduced effectiveness to prevent condensation from building up in the exhaust system. The condensation could otherwise lead to corrosion, and damage the effectiveness of the engine and exhaust system.

That is permissible and not illegal, a spokesman told Reuters.

German daily newspaper Handelsblatt first reported the EPA request for information, the news agency noted. In its Monday edition, the paper quoted Christopher Grundler, director of the EPA’s Office of Transportation and Air Quality, as saying: “We know about the lawsuit. We have contacted Mercedes and requested the test results for the US diesel engines.”

An EPA spokeswoman Allen confirmed Grundler’s comments for Reuters.