Over the weekend, Germany's auto regulator told Daimler that it would have to recall 42,000 Mercedes-Benz diesel vehicles after the group discovered illegal software on the cars that would reduce the effectiveness of the emissions-control system.

Daimler said Sunday night that it would take a one-time charge of hundreds of millions of euros against the upcoming quarter's earnings to deal with the new accusations, but it disputed the government regulator's determination that the software in question was illegal. According to the Wall Street Journal , Daimler plans to formally object to the claims.

The accusation against the German automaker is similar to accusations lobbed against Volkswagen Group starting in 2015. The US Environmental Protection Agency accused VW Group of including illegal software on its diesel vehicles to ensure that the diesels would pass emissions limits imposed by the US. Ultimately, VW Group ended up spending tens of billions of dollars on regulatory fines and vehicle buybacks in the US and the EU.

Today, the Daimler vehicles in question are Mercedes-Benz-brand vehicles that are only sold in the EU. According to a WSJ source, the issue relates to a coolant thermostat in the cars that protects parts of the engine. The related software is found on vehicles made between 2012 and 2015. The WSJ says the type of coolant thermostat used on the diesel vehicles in question is generally found on cars with catalytic converters that don't use selective catalytic reduction, an emissions-reduction technique that uses urea to reduce nitrogen oxides to less-harmful forms. But the GLK 220 CDI 4MATIC Mercedes-Benz models that must be recalled do appear to use selective catalytic reduction.

Daimler said it notified the government regulator about the existence of this software last year. Last June, Daimler was ordered to conduct another, larger recall of diesel vehicles across Europe due to a separate illegal-software issue related to emissions. Separately, Daimler, BMW, and Volkswagen Group have been under investigation by the European Union Commission for allegedly conspiring to hinder emissions reduction technology in diesel and gas vehicles.