STUTTGART/FLENSBURG (dpa-AFX) - Mercedes-Benz must recall tens of thousands of diesel cars in Germany alone due to renewed allegations of illegal emissions technology. The German Federal Motor Transport Authority (KBA) has issued a corresponding notice, the Stuttgart-based car manufacturer announced on Wednesday in response to an inquiry. A low six-digit number of vehicles are expected to be affected. The KBA could not initially be reached for comment. Spiegel" and Bayerischer Rundfunk had previously reported on the order.

According to the manufacturer, the order relates to various Euro 5 and Euro 6b diesel models. The cars therefore require a software update. Customers will be informed in writing if their vehicle is part of the KBA order and an update needs to be installed, it said.

Reason for the recall: thermal windows

The reason for the recall is so-called thermal windows, which were also used as standard by other manufacturers. Normally, some of the exhaust gases are burned directly back into the engine - for example, to emit fewer toxic nitrogen oxides. Depending on the outside temperature, however, this mechanism is automatically throttled back - to protect the engine, as the manufacturers say.

However, the European Court of Justice (ECJ) clarified in a ruling in 2022 that software that allows higher emissions of pollutants "for a large part of the year" is generally inadmissible. Thermal windows to protect the engine are only legal if no other solution can avert risks.

Mercedes: Extensive cooperation with the KBA

Following the ECJ ruling, the KBA has further developed its legal opinion in this context and has now requested Mercedes-Benz to change the corresponding calibrations in the engine control unit of certain vehicle variants, a spokeswoman for the car manufacturer announced. She continued: "Until the ECJ ruling, the European type approval authorities generally considered such temperature controls for exhaust gas recirculation to be permissible". The company is cooperating fully with the KBA.

Mercedes has had to deal with exhaust gas allegations for years. Since 2018, the KBA has already issued several recall notices against the manufacturer due to inadmissible exhaust technology. Hundreds of thousands of vehicles were affected in Germany alone. Since the scandal came to light, the Stuttgart-based car manufacturer has also been repeatedly taken to court. So far, more than 30,000 consumers in Germany have taken legal action. In addition, a test case brought by investors has been under negotiation since September, demanding hundreds of millions of euros in compensation for losses incurred./jwe/DP/jha