Opel will appeal a mandatory recall ordered by the German Federal Motor Transport Authority (KBA) for certain types of diesel vehicles which were allegedly fitted with illicit defeat devices, the Ruesselsheim-based carmaker confirmed on Friday.

The German magazine SPIEGEL reported that Opel sought to prevent an immediate recall of nearly 100,000 diesel vehicles from traffic by legal appeal. According to a spokesperson for the responsible Schleswig Administrative Court, a decision in the case is expected to be reached between late November and early December.

The German transport authority recently ordered the mandatory recall for 96,000 Opel vehicles built between 2013 and 2016 in response to suspected emissions-cheating practices. Unlike its larger domestic rivals Volkswagen and Daimler, the PSA subsidiary had so far evaded formal judicial scrutiny in the dieselgate scandal.

During a hearing at the ministry of transport back in July, Opel was asked to provide information about the function of exhaust system defeat devices in three of its models. A spokesperson for the ministry said at the time that it was too early to reach conclusions about the "legitimacy" of the technology in question.

The subsequently-ordered recall affects Opel Insignia, Zafira and Cascada models in which the KBA said it discovered motor software which understated actual NOx emissions during normal operations, a claim that was rejected by Opel. The Federal Environmental Agency (UBA) estimates that diesel cars are responsible for more than 50 percent of harmful NOx emissions in Germany.

Opel is currently in the midst of a closely-watched struggle to improve profitability at the 156-year-old firm. The carmaker wants to focus on producing lower volumes of vehicles with higher profit margins in the future and has launched a far-reaching program of corporate reforms since being acquired by PSA in 2017.