Daimler may issue a recall for over 600,000 diesel vehicles, including thousands of C-Class and G-Class models, if proven to have emission cheating technology.

German publication Der Spiegel claims that Germany’s transport authority, KBA, is investigating claims that diesel C-Class and G-Class vehicles have a similar cheat device to certain diesel versions of the Vito van.

Mercedes-Benz was recently accused of using a cheat device in variants of its Vito van fitted with a 1.6-liter four-cylinder engine from Renault. The Federal Ministry of Transport issued an immediate recall of the van in the middle of last week. Daimler asserts that the car will receive a software update to ensure it complies with all relevant regulations.

According to a source, Federal Transport Minister Andreas Scheuer personally “instructed the Federal Motor Transport Authority to investigate further suspected cases at Mercedes immediately.”

Renault, the manufacturer of the aforementioned 1.6-liter diesel, was suspected of using diesel cheat devices in 2016 but has denied all allegations. Daimler chief executive Dieter Zetsche was reportedly summoned to the German Transport Ministry over suspicions regarding the Vito.

If Daimler is forced to issue a recall for over half a million C-Class and G-Class models, it will inevitably cost the automaker millions, if not hundreds of millions of dollars.