This appears to be illegal as the vehicle no longer complies with the Vehicle Construction and Use Regulations 61a(3).
Please see www.legislation.gov.uk/uksi/1986/1078/contents/made
The DPF is the most expensive part of the exhaust system and control the emissions released from the vehicles exhaust. The emulator that is fitted to our sons car tells the engine management computer that everything is working as it should through bypassing what the manufacturer initially installed to comply with UK and EU legislation on vehicle construction.
From February 2014 the removal of the DPF will result in an immediate fail at the MOT. A vehicle without a DPF is not merely non-standard but illegal for use on the road.
Our son saw the car advertised on a website and went to a garage to make the purchase. The car was sold as standard and no mention of any alterations to any part of the vehicle. This also formed part of the documentation in applying for insurance i.e. the car had not been modified in any way. Is it not the sellers responsibility to tell him of the alterations rather than the buyer removing the exhaust to examine if the filter is complete and not merely a tube in the exhaust system?
As to the MOT fail being illegal, numerous web based documents are published about the practice of removing the filter but the most important would appear to be the following,
In response to your question above our son is not a vehicle mechanic. Until a few weeks ago the phrase Diesel Particulate Filter was something non of us had ever heard of. He did not specifically ask if the vehicle had one or not so he could not be given a false or misleading answer.
With regard to the MOT if the car had been bought without an MOT he would have bought it under those terms. The car was bought with an MOT and was therefore sold as a road worthy vehicle, as any other three year old vehicle would be.
The reason for my initial questions are, can a garage sell a vehicle that is not fit for use on the road in the UK without telling the buyer that the alterations have been made? This would allow the buyer to decide whether or not to buy the vehicle and carry out the necessary work to make the vehicle fit for use on the road.
Am I right in understanding that your view is that there is nothing illegal in using the car on the road with the DPF removed? As the car currently has a valid MOT is the car road legal and would his insurance still be valid in any claim, now that he is aware of the removal of the DPF?