STUTTGART, Germany – Germany’s federal transport authority, the KBA (Kraftfahrtbundesamt), has placed a registration ban on the Porsche Cayenne Diesel due to the discovery of what it describes as suspect emissions-manipulation software.

The ban, confirmed by German transport minister Alexander Dobrindt on Thursday, comes after KBA testing revealed the Porsche model is fitted with software that manipulates carbon-dioxide emissions by switching to a so-called warm-up strategy mode when it detects they are undergoing testing on a rolling road. The process provides a lower CO2 rating than would be achieved otherwise.

The Cayenne Diesel is powered by an Audi-developed and produced turbocharged 3.0L V-6 diesel – the same unit used by Audi in a raft of different models, including the A4, A6, A8, Q5 and Q7, and recalled by that brand earlier. The engine also is offered in the Volkswagen Touareg.

In the Cayenne Diesel, the Audi V-6 develops 262 hp and is claimed to return 35.6 mpg (6.6 L/100 km) on the combined European consumption test cycle for average CO2 emissions of 173 g/km.

As well as placing an immediate ban on the registration of the Cayenne Diesel, the KBA also ordered a recall of up to 22,000 vehicles already sold in Germany.

The Cayenne Diesel registration ban comes after tensions between Porsche and Audi were strained following comments made by Porsche union boss, Uwe Hueck, on Monday.

In a pointed attack on Volkswagen sister company Audi, Porsche’s Hueck said: “We feel deceived by Audi. The supervisory board should fire the management.”

In a statement released today, Porsche says the recall will involve a software update for the engine controls.