Euro 5 vs Euro 5+ on Petrol Motorcycles – What’s the Difference? And What’s Coming Next?
If you ride a modern bike, you’ve probably seen Euro 5 or Euro 5+ in the spec sheet… but what does that actually mean?
Here’s the quick breakdown 👇
Euro 5 (introduced 2020)
Euro 5 set strict limits on emissions for new motorcycles, especially:
- Carbon monoxide (CO)
- Hydrocarbons (HC)
- Nitrogen oxides (NOx)
- Particle numbers on some direct-injection engines
- Stricter noise and durability requirements
Most modern bikes already have:
✔ catalytic converters
✔ lambda sensors
✔ precise fuel injection and ECU mapping
Euro 5+ (also called Euro 5b)
Euro 5+ isn’t a whole new standard—it’s a tighter second phase of Euro 5.
For petrol motorcycles, this mainly means:
✅ more accurate real-world testing
✅ tougher on-board diagnostics (more sensors, stricter fault detection)
✅ more stringent durability of emission controls
❗ stricter testing of particulate numbers on direct-injection engines
What riders actually notice:
- ECUs are fussier
- Catalytic converters are more integrated into the exhaust design
- Exhaust mods trigger engine lights more easily
- Bikes must stay cleaner for longer during their life
What About Euro 6? And When Will It Hit UK Motorcycles?
Euro 6 already applies to cars, but motorcycles have not yet moved to Euro 6.
The EU is preparing a “Euro 6 for motorcycles” (known as Euro 6 for L-category vehicles). The UK usually follows EU standards for bikes with some delay.
Expected UK timeframe:
- No official published date yet, but most industry analysts expect around 2027–2030
- It will likely mean:
- Stricter NOx limits
- Wider use of particulate filters on petrol bikes
- More complex ECUs and lambda sensors
- More real-world (RDE-style) emissions testing
When Euro 6 arrives, exhaust and ECU modifications will get even trickier.
Thinking of Removing the Catalytic Converter? Here’s What You MUST Know
Removing the cat (“de-catting”) is common on older bikes, but modern Euro 5/5+ bikes depend on it for tuning and legal compliance.
If you remove the cat on a Euro 5/5+ bike and still want it to run properly:
You will generally need
- ECU remap or fuel controller
- Lambda sensor adjustments or eliminators (if used)
- Correct fueling to avoid running lean
- Sometimes a modified mid-pipe to ensure proper exhaust back-pressure
What happens if you don’t:
- Engine warning lights
- Limp mode (on some bikes)
- Overheating exhaust valves
- Poor low-end running
- MOT failure if visible tampering is obvious (see below)
UK Law: What Riders MUST Know About Modifying Euro 5/5+ Motorcycles
On Road Use
In the UK it is illegal to use a motorcycle on public roads if you have:
❌ tampered with or removed emissions equipment (including catalytic converters)
❌ modified the ECU so the emissions exceed the approved type-approval standard
This applies even if the bike still passes an MOT. MOT is not the same as type-approval compliance.
MOT Rules
- Motorcycles currently do not have an emissions test at MOT
- BUT testers must fail a bike if a catalytic converter that was originally fitted has clearly been removed on a bike that required it for approval
Insurance
Removing a cat is a material modification.
If you don’t declare it:
→ insurance can be invalidated
→ claims may be rejected
Police / Roadside checks
Roadside enforcement officers can:
- Inspect for missing emission equipment
- Check for ECU tampering
- Issue fines or prohibit the bike from being ridden
Final Thoughts
- Euro 5+ is basically Euro 5 with stricter testing and tougher ECU diagnostics.
- Euro 6 for motorcycles is coming later this decade and will push emissions even lower.
- If you modify your exhaust and remove the cat, be prepared for ECU work, sensor issues, and legal risks.
- Always declare mods to your insurer and make sure you know the legal implications.
