Every car sold in the UK is built to a Euro emissions standard — a legal limit on what may come out of the tailpipe. The standard your vehicle carries decides which replacement emissions parts are approved for it, and increasingly, where you can drive without paying a charge.
The standards at a glance
Euro standards have tightened steadily since they were introduced alongside the compulsory fitting of catalytic converters to new petrol cars. The dates below are when each standard applied to new car registrations (approval dates for new models came slightly earlier):
| Standard | New cars from | What it meant in practice |
|---|---|---|
| Euro 1 | 1993 | Catalytic converters become compulsory on new petrol cars |
| Euro 2 | 1997 | Tighter CO and combined HC+NOx limits |
| Euro 3 | 2001 | Separate HC and NOx limits; cold-start testing |
| Euro 4 | 2006 | NOx and particulate limits halved; first DPFs appear |
| Euro 5 | 2011 | Particulate limits make DPFs effectively universal on diesels |
| Euro 6 | 2015 | Big diesel NOx cut — AdBlue/SCR systems appear; GPFs follow on petrols |
Petrol and diesel engines produce different emissions, so each standard sets different limits for each fuel — which is one reason petrol and diesel emissions parts are not interchangeable.
Why your Euro level matters when buying parts
The vehicle carries the Euro level, and the law requires replacement emissions parts to be approved for the vehicle at that level. External housings can look identical between parts approved to different standards — the differences are internal. So always match the part to your vehicle and engine (our part finder does this for you) rather than by appearance or dimensions, and check the Euro level shown on the product page. More on the legal side in type approval and the law.
Clean-air zones and charges
Cities across the UK and Europe now restrict or charge higher-polluting vehicles, and eligibility is set by your Euro standard. London’s ULEZ requires at least Euro 4 for petrol and Euro 6 for diesel vehicles to escape the daily charge; Clean Air Zones in other UK cities use similar thresholds, as do low-emission zones in France, Germany, Italy, the Netherlands and elsewhere. If you drive into cities regularly, your Euro level is worth knowing before it becomes an expensive surprise.
Finding your vehicle’s Euro standard
- Check section D.2 or the notes of your V5C logbook — newer documents state it directly.
- Use the registration-based checkers provided by Transport for London and the government’s Clean Air Zone service — both report your vehicle’s compliance.
- If in doubt, the registration date in the table above is a reliable rule of thumb, and your dealer or manufacturer can confirm it from the VIN.