ECJ on the diesel scandal: When are thermal windows necessary?

The European Court of Justice is once again dealing with thermal windows used in exhaust gas cleaning. Key questions are: Was Deutsche Umwelthilfe allowed to sue at all? And: When are thermal windows “necessary” and exceptionally permissible?

The so-called thermal window is again an issue at the highest court in the EU – i.e. the question of whether the cleaning of exhaust gases in cars can be completely or partially switched off in a certain temperature range. As early as December 2020, the European Court of Justice (ECJ) had laid down a fundamental principle: Switching off simply to protect the engine from dirt and wear is not possible.

In July of this year, the Court of Justice specified its line. Since complained VW customers from Austria, who wanted to return their cars because of the diesel scandal. After the software update, a thermal window was also created. The exhaust gas cleaning only took place between 15 and 33 degrees. According to the ECJ, this is clearly an inadmissible defeat device. Temperatures below 15 degrees would be normal in the EU. Therefore, the limit values ​​for exhaust gases must also be observed when it is colder than 15 degrees.

Concrete danger or not?

The European judges say very clearly: Simply reducing exhaust gas cleaning to protect certain engine parts does not make the whole thing permissible. But – and that’s what it’s been about since then: Things could be different if switching off is necessary to avoid damage that could lead to a specific danger when operating the car.

The exception is important. Because now it is important: Could the possible damage to the engine become a concrete danger when driving? Volkswagen said in the summer after the last ECJ decision: Yes, the risks would be so serious that they pose a concrete danger when operating the vehicle – apart from the fact that the company says that the exhaust gas cleaning system would only be reduced to below ten degrees anyway.

Complaint by the German Environmental Aid

Now the ECJ has another opportunity to say something on the subject. This time it’s about a lawsuit from Germany. The German Environmental Aid has objected to the fact that the Federal Motor Transport Authority has waved through the thermal window. On the occasion, the supreme court must also clarify whether the German Environmental Aid is allowed to sue at all – i.e. whether a non-profit environmental organization can take action against the authorities if they find their decisions wrong.

In addition to this important preliminary question, it is conceivable that the Court of Justice will say something else about the thermal window: how strictly is meant with the protection of clean air, what state of the art VW must take into account and whether it should not also play a role, how expensive the changeover for the company will.

Not the last decision in the diesel scandal

Today’s decision will certainly not be the last in the diesel scandal. It is still an open question whether the ECJ is not more customer-friendly than the German courts, whether car manufacturers may also have to pay if they cannot be proven to have acted immorally, but were only negligent in dealing with the emission regulations.

And the big questions are: Do the customers who suffered damage really have to be credited for using the car before the compensation was paid? The German courts had previously said that there was less compensation overall because of the use.