German Transport Minister Alexander Dobrindt told reporters in Berlin on Friday that an emissions probe monitored by the Federal Motor Transport Authority (KBA) had revealed irregularities in 16 brands, including Audi, Porsche, Daimler and Opel.

He confirmed earlier reports by Reuters that affected carmakers would voluntarily recall a total of 630,000 vehicles to correct software measuring car emissions.

A number of foreign auto makers such as Renault had also signaled their willingness to make corrections to the built-in control software, Dobrindt added.

Not to be compared with VW's scam

The large-scale probe had been ordered by the Transport Ministry in the wake of the pollution scandal that had engulfed Volkswagen after it admitted in September last year to cheating on diesel exhaust tests around the world.

Dobrindt made it clear that no other carmaker investigated had been found to use illicit defeat devices so as to deliberately thwart emissions tests in the laboratory.

But real emissions were found to be much higher than stated by the carmakers' software because of a special waste gas purification control unit, which Dobrindt said did not violate EU law.

The unit is meant to prevent engines from being damaged when it's warm outside, in which case it gradually reduces emissions purification to avoid overheating.

The German transport minister said doubts as to whether the system had to be triggered at temperatures as low as 18 degrees Celsius were justified, however, and asked carmakers to rectify the situation.

hg/hch (dpa, Reuters)