What has changed since 2023
Since 1 January 2023, periodic inspections (MFK) check not only the safety of the vehicle but also the correct operation of the particulate filter of diesel vehicles, by measuring the number of particles in the exhaust.
Which vehicles are affected
- Diesel cars and vans with emissions code B5b or higher.
- Lorries and buses with emissions code E06 or higher.
The code is shown in the vehicle registration document, in field 72.
The limit
The limit value is 250,000 particles per cubic centimetre. The vehicle passes the check only if it stays below it.
Why a warning light that is off is not enough
According to the Swiss garage association (AGVS), a share of vehicles exceed the limit in inspections, and the most frequent cause is a filter with micro-cracks. The vehicle’s diagnostic system does not always detect these cracks, so the warning light can stay off even if the filter is not working as it should.
What we can do. If you have an inspection coming up or notice symptoms, contact us: we assess the case and tell you whether work makes sense. We cannot guarantee the outcome of an official inspection, and a damaged filter may not be regenerable.
What to do in practice
- Check the emissions code in the registration document (field 72).
- If the vehicle is covered, have the condition of the filter assessed before the inspection date.
- If you notice symptoms (warning light on, loss of power, strong smell from the exhaust), have the filter assessed.
- For up-to-date details, contact the competent cantonal authority (in Ticino, the Sezione della circolazione, the road traffic office).
General information, updated as of 26 October 2026; the rules may change. Sources: AGVS, Infoblatt Dieselpartikelfilter (2023, PDF in German); AGVS, Fokus Technik (2024, PDF in German).