UK law can work very strangely at times, eg things that are legal to be sold but illegal to use!

I suspect EGRs and DPFs fit the same sort of anomaly - that it's not specifically illegal for a workshop to remove them, nor the owner to drive around without it, but that the MoT test is intended to detect such omissions and fail such a car.

The Type Approval for the car includes all the emission control equipment fitted as standard. Technically, if a car is modified out of this, then it no longer meets Type Approval.

How different countries choose to test to ensure that cars are legal, and to what extent they do so, is very much down to them. For example, we have tha MOT test annually from 3 years old. The minimum requirement in EU law is for a test every 2 years from 4 years old.

I do know that BMW (for example) have very much ensured that on the newer generations of engine, blanking the EGR produces a permanent limp mode that has proved to be impossible to code out - I've seen various discussion groups on this, and it seems nobody has managed to get round this, even after 5+ years.

Thanks for the posts. To state the obvious - its a pity there are not straightforward and understandable regulations which are legally enforceable. Seems to me that if you change a motor in a way that worsens the environmental effects it should be an offence.

Not so sure it should be an offence. Rather that the car should be prohibited from use until restored to original condition.

But to realistically inspect cars to ensure that they are 'as original' would involve huge expense on the current MOT. Even then it would not detect 'chipping' or remaps, but only physical items - EGRs, DPFs, cats, etc.

And a legal minefield about what ECU refreshes are permitted by the manafacturer without requiring new Type Approval.

No - it was a fair question. But I think you'll be a lot happier if your next car is petrol-powered.

there's a statement from VOSA (I think) about this very subject (removal of EGR) in this months' Car Mechanics within the article on Turbochargers.

If I remember tonight I'll take a look and copy it upto here, though this might just be more heresay!

Car Mechanics asked the DVSA for their response to fitting an EGR blanking valve and they said : "DVSA's priority is to help you keep your vehicle safe to drive, ensuring that it meets required roadworthiness and environmental standards. Vehicles may fail the MoT where emissions control equipment has been tampered with but irrespective of the MoT such modification is an offence*. DVSA continues to work with DfT to persue such offences, including taking disciplinary action against any MoT garages found to be conducting modifications."

* Road vehicles (construction and use) regulations (Regulation 61a(3)). Removal of an EGR valve, diesel particulate filter etc. will almost invariably contravene these requirements, making the vehicle illegal for road use. The potential penalties for failing to comply with Regulation 61a are fines of upto £1000 for a car or £2500 for a light goods vehicle.

Edited by The Gingerous One on 26/07/2017 at 13:40

I have received a letter today from Department for Transport that confirms advice given on here. Thanks. Some motorists will be getting a surprise. Should've gone on a forum.