Peugeot, Citroen under formal investigation after allegations of cheating in diesel emissions tests
Having so far escaped criticism for their emissions performance, PSA Group have become the latest manufacturers to be investigated over test cheating
FRENCH prosecutors have opened a formal investigation into suspected diesel emissions test-cheating by carmaker PSA Group, a court official said on Monday.
According to official reports, the probe was opened earlier this month into alleged consumer fraud offences.
The manufacturers of Peugeot, Citroen and DS cars became the fourth carmaker to be referred to prosecutors by France's DGCCRF consumer fraud watchdog in February over suspected diesel test manipulation.
Following the referrals of Volkswagen, Renault and Fiat Chrysler, the probe dealt a major a setback to the Paris-based company, whose emissions performance had so far escaped major criticism.
PSA, which denies any wrongdoing, said on Monday it had "taken note" of the prosecutors' decision to open a full investigation.
The carmaker vowed to "defend its interests" as a spokesman insisted PSA "respects regulations in all countries where it operates."
The spokesman added its vehicles had never been equipped with emissions detection software enabling it to cheat pollution readings.
A judicial source told AFP the Paris prosecutor on April 7 opened an investigation into claims that PSA might have rigged controls which could "render its merchandise dangerous for human or animal health".
The manufacturing group said it would "defend its interests and those of its 180,000 workforce, its customers and partners".
The accusations against PSA are the latest chapter in a huge scandal which erupted in September, 2015, when Volkswagen, Europe's biggest carmaker, admitted to fitting 11 million cars -- 8.5 million in Europe -- with devices allowing them to fool emission tests.
Following VW's exposure, several European countries launched their own investigative test programmes.
They found on-road nitrogen oxide (NOx) emissions more than 10 times above regulatory limits - for some GM, Renault and Fiat models - and widespread use of devices that reduce exhaust treatment in some conditions.
Carmakers have broadly invoked a European legal loophole allowing such software for safety purposes or engine protection.
PSA diesels under the current Euro 6 standard have cleaner emissions than many mass-market rivals, thanks to their standard deployment of costly selective catalytic reduction (SCR).
But in a government-backed testing programme last year, five PSA vehicles of the last Euro 5 diesel generation emitted significantly higher NOx in motorway driving conditions when engine temperatures were increased.
By design, the cars' so-called EGR emissions treatment is deliberately reduced at higher temperatures to improve fuel efficiency and carbon dioxide (CO2) emissions in out-of-town driving, where NOx and particle output is less critical, PSA engineering chief Gilles Le Borgne said in February.
The company last year began an independently certified real-world CO2 emissions-testing programme and began publishing results measured for all its vehicles on the road.