Porsche investigates alleged manipulation of petrol engines

Porsche has opened internal investigations into alleged software and hardware changes made to engines after they were type-approved by Germany's Federal Motor Transport Authority (KBA).

The investigation, which Porsche says is focused on possible illegal engine manipulation, is claimed to centre around engines fitted to Panamera and 911 models produced between 2008 and 2013.

The alleged changes are said to have been used to manipulate exhaust gas emissions, in a manner similar to the illegal filter-switching engineered into various diesel engines supplied to Porsche by sister company Audi.

In a statement made to Germany's Handelsblatt newspaper, Porsche confirmed that its internal investigation into possible illegal software and hardware engine changes, saying: "We found a few indications of possible misconduct".

Porsche has also confirmed that it "proactively" informed the KBA, the Stuttgart public prosecutor and US authorities about the possible misconduct in "early summer".

The KBA has opened its own investigation into Porsche's claims of misconduct.

Meanwhile, Audi is facing allegations of possible exhaust gas manipulation in petrol engines in a case brought before the Offenburg district court in Germany.

The case alleges the turbocharged 2.0-litre four-cylinder petrol engine in the Q5 uses a steering wheel sensor to trigger a switching off of the selective catalytic reduction filter, in the process leading to significantly higher levels of NOx emissions than those achieved in testing.

The sensor, which Audi already acknowledges was used to manipulate diesel engine emissions, recognises when the car isn't on a rolling road, as used in emissions testing, and switches off the filter, providing a claimed boost in performance at the expense of extra emissions.

According to court papers, NOx emissions are up to 24.5% higher when the alleged sensor used by the Q5 2.0 TFSI detects lock is being applied and triggers the switching off of the exhaust gas filter.