Canadian branches of the Volkswagen, Porsche and Audi brands have all issued stop sales in light of the unexpected U.S. Environmental Protection Agency notice received Monday.

This news comes after the five companies under Volkswagen’s umbrella that are involved in the sale of its V6 diesel engines in the United States received notification from the EPA alleging that their 3.0 liter V6 engines also contain defeat devices that circumvent EPA emissions testing.

Volkswagen later denied those allegations.

Then on Wednesday, Porsche Cars Canada decided to voluntarily discontinue sales of model year 2014 through 2016 Porsche Cayenne Diesel vehicles until further notice.

In light of the stop sale, Porsche Cars Canada said, “We are working intensively to resolve this matter as soon as possible. Customers may continue to operate their vehicles normally.”

Audi Canada is stopping the sale of 2014-2016 A6, A8 and Q5 models, as well as the 2013-2015 Q7 models.

And according to a representative from Volkswagen Canada, the nameplate is ceasing sales for its diesel Touareg vehicles.

This second diesel-related notification of violation for the year from the U.S. EPA — sent to Volkswagen AG, Audi AG, Volkswagen Group of America, Porsche AG and Porsche Cars North America — outlines that the diesel engines containing the alleged defeat devices from model year 2014 through 2016 vehicles emit up to nine times the EPA’s standard of nitrogen oxide.

This list, provided by the EPA, covers only vehicles of these models that include the 3.0 liter diesel engines, which it says includes approximately 10,000 vehicles already sold in the U.S. since 2014 along with an unknown volume of 2016 vehicles, which include:

• 2014 VW Touareg
• 2015 Porsche Cayenne
• 2016 Audi A6 Quattro
• 2016 Audi A7 Quattro
• 2016 Audi A8
• 2016 Audi A8L
• 2016 Audi Q5

Via an official statement, Volkswagen denied that its V6 TDI engines contain defeat devices. Here is the full statement:

"The United States Environmental Protection Agency (EPA) informed Volkswagen Aktiengesellschaft on Monday that vehicles with V6 TDI engines had a software function which had not been adequately described in the application process. Volkswagen AG wishes to emphasize that no software has been installed in the 3-liter V6 diesel power units to alter emissions characteristics in a forbidden manner," the statement said. "Volkswagen will cooperate fully with the EPA to clarify this matter in its entirety."

Porsche Cars North America issued its own official statement regarding the allegations toward the diesel variant of the Porsche Cayenne.

"We are surprised to learn this information. Until this notice, all of our information was that the Porsche Cayenne Diesel is fully compliant," the statement said. "Porsche Cars North America will cooperate fully with all relevant authorities."

Porsche Cars North America issued a stop-sale Tuesday evening: "Porsche Cars North America, Inc. today decided, in view of the unexpected U.S. EPA notice received yesterday, to voluntarily discontinue sales of model year 2014 through 2016 Porsche Cayenne Diesel vehicles until further notice."