Replacement catalytic converters and DPFs are legally controlled parts in the UK. This page explains what type approval means, when the law requires it, and how to tell whether a part qualifies.
What type approval means
Type approval is independent certification that an aftermarket part performs to the standard of the original equipment it replaces. For emissions parts that covers the things that matter: tailpipe emissions, noise, back pressure and fuel efficiency. Testing is overseen by a national approval authority — in the UK the Vehicle Certification Agency (VCA), in Germany the TÜV — and an approved part carries a certification mark and is approved for specific vehicles, not in general.
That last point matters more than people expect. Two parts for different cars can share identical housings and pipework yet have completely different internals and approvals. A part that physically bolts on is not necessarily approved — or legal — for your vehicle and its emissions standard.
What the law requires
- Catalytic converters: if your vehicle was first registered on or after 1 March 2001, any replacement cat must be type-approved for that vehicle. Vehicles first registered before that date are exempt, though the replacement should still perform equivalently to the original.
- DPFs: replacement filters fitted to Euro 5 or later vehicles (broadly, diesels registered from 1 January 2011) must be type-approved.
- Under the Motor Vehicles (Replacement of Catalytic Converters and Pollution Control Devices) Regulations 2009, supplying non-approved parts where approved ones are required is an offence carrying fines of up to £5,000.
Separately, removing a DPF altogether is illegal — it’s an MOT failure and an offence to drive the vehicle.
A note on “sports cats” and de-cat pipes
High-flow “sports” catalytic converters and de-cat pipes sold “for off-road use” are generally not type-approved for road vehicles. Fitting one to a post-2001 road car doesn’t just risk an MOT emissions failure — the vehicle no longer meets the standard it was registered to, with the legal and insurance consequences that follow.
Where CatHive parts stand
The parts we sell are manufactured by BM Catalysts, Europe’s largest independent manufacturer of catalytic converters, DPFs and related exhaust parts. Type-approved parts in the range carry the “H” suffix on the part number — short for homologated, the industry term for type-approved (see understanding our part numbers). Our part finder matches parts to your exact vehicle and engine, and each product page lists the Euro standard the part is designed for — check it against your vehicle’s own standard, which you can confirm using the steps in our Euro standards guide.