Older diesel vehicles that do not receive a green sticker or cannot profit from exemption regulations must not enter the low emission zone. However, it is not always necessary to replace vehicles since they can often be retrofitted with a particulate filter. This applies in particular to vehicles with a yellow sticker (diesel vehicles with Euro 3).
Only certified filters with a general operating permit by the Federal Motor Transport Authority may be used for retrofitting. The technical requirements for particulate filters are specified in Annex XXVI (Cars/light commercial vehicles) and Annex XXVII (Trucks) of the German Road Traffic Licensing Regulations (StVZO).
The workshop will issue a certificate of the installation of the filter system. The licensing office will make an entry in section 22 of the vehicle documents based on this certificate and may award a higher category sticker.
A vehicle’s emissions standard classification (Euro norm) and its corresponding classification for German road tax will not change as a result of a retrofit, since it does not reduce the other regulated pollutants.
The long-standing funding for particulate filter retrofit by the Federal Government expired in 2016.