Farcical Enforcement of Emission Regulations  

20 June 2012


Earlier this year I noticed a popular Internet forum discussing problems with Diesel cars equipped with Diesel Particulate filters (DPF). These are designed to capture and oxidise any solid and liquid material in the exhaust thereby reducing particulate emissions. However, if the temperature of the exhaust fails to reach a high enough temperature (due to avoiding higher speeds for example), oxidation can fail, and the particulate material accumulates inside the filter until it becomes blocked.  A blockage is usually indicated on the cars on-board diagnostic system.


The popular solution according to these forums is to - yes you’ve guessed it - remove the DPF entirely rather than replace it!  This rarely prevents the car from failing the emissions test.  This is partly because the MOT Diesel car emission test regulates smoke which is an optical measure of the non-gaseous exhaust, whilst particulate (which the DPF is more specifically designed to control) measures mass. This is due to the need for greater simplicity, speed and lower costs necessary for routine emissions testing.  


However, each vehicle is type approved to conform to a mass based particulate limit, and to remove the DPF or tamper with the electronic management controls without being subject to type approval is illegal (see Directive 2010/48/EU summarised below in the email exchange). This hasn’t prevented a small industry of DPF removal and engine adjustment outfits marketing themselves to customers who wish to replace this troublesome but necessary equipment. These firms also  provide misleading or false information. For example:


Does removal of the DPF/ FAP result in a MOT failure?  

Simple answer is NO. Diesel particulate filters are surplus to requirements.... The removal process is 100% legal, and this can be confirmed by VOSA.


Yet the official agencies seem to be lethargic at enforcing regulations, thereby encouraging this proliferation of this activity (see Email exchange with VOSA, VCA etc below)..


This unofficial tolerance of ‘tampering’ is nothing new. I used to work for one of the research arms of the Dept of Transport which was sold off, and whose buildings are partly occupied by one such tampering organisation located not an arms throw away from what used to be our emissions test laboratory!  


In conclusion: DPFs when functioning correctly are effective at reducing particulate, although this adds greater cost and complexity to modern Diesel cars. Unfortunately, they also serve the purpose of allowing government officials to take the moral high ground in that they endorse the highest standards of particulate emission legislation, and admit only vehicles on the road which theoretically conform to these standards. Of course new and honest second hand car buyers will take the brunt of this cost, whilst the public is still subject to the air pollution resulting from the illegal backyard tampering of these systems!






I wrote to Vehicle and Operator Services Agency (VOSA) and Vehicle Certification Agency (VCA) at the Department of Transport describing these problems with the following predictable reactions!


These Emails were sent to the VCA after I received a disinterested response from VOSA.  My Mails are in blue, the responses are in Red.


From: Stephen [mailto:owlsmoor -at- googlemail.com] Sent: 23 January 2012 09:13 To: Darren Whitecross Subject: query: illegal tampering with emission systems


Is Directive 2010/48/EU now in force in the UK?



COMMISSION DIRECTIVE 2010/48/EU of 5 July 2010 adapting to technical progress Directive 2009/40/EC of the European Parliament and of the Council on roadworthiness tests for motor vehicles and their trailers

In the interests of road-safety, environmental protection and fair competition it is important to ensure that vehicles in operation are properly maintained and tested, in order to maintain their performance as guar­anteed by type-approval, without excessive degradation, throughout their life-time

Article 2 1. Member States shall bring into force the laws, regulations and administrative provisions necessary to comply with this Directive by 31 December 2011 at the latest,

4. MINIMUM INSPECTION REQUIREMENTS The inspection shall cover at least the items and use the minimum standards and methods listed below. Reasons for failure are examples of defects that may be detected.....

8.2.1. Petrol engine emissions Exhaust emissions control equipment Visual inspection (a) Emission control equipment fitted by the manufacturer absent, modified or obviously defective.

8.2.2. Diesel engine emissions Exhaust emission control equipment Visual inspection (a) Emission control equipment fitted by the manufacturer absent or obviously defective  



If so, what measures do you intend to take against organisations which openly tamper, recalibrate or remove emission control systems?  This has become a major industry.




e.g. Quote


Does removal of the DPF/ FAP result in a MOT failure? Simple answer is NO. Diesel particulate filters are surplus to requirements, and all you need to pass your MOT’s is a fully working catalytic converter. While removing the DPF/ FAP we never touch your cat, so as long as everything else in your car works as it should- you will not have MOT problems. The removal process is 100% legal, and this can be confirmed by VOSA.


Indeed VOSA appear uninterested or unaware and just refer to yourselves!


Quote: Unfortunately VOSA do not handle enquiries of this type, as we are only responsible for the oversight of the MOT standards as laid down in the appropriate legislation.......

We are not aware of any plans to introduce DPF checks at this time.


I am aware of this document, but this seems to deal with organisations which fit devices, not remove them altogether!




Most of the public still believe that passing the MOT emission limits is sufficient proof that vehicles conform to the required in-service emission standards. Isn’t it about time this change was more widely publicised, especially in London who are using increasingly desperate measures to reduce particulate emissions?


I am just an independent bystander with no affiliations, I but have worked in this area in the past!


Regards Stephen



From: Mohammed Farooq

Sent: Wednesday, January 25, 2012 6:27 PM

To: owlsmoor -at-googlemail.com

Subject: FW: query: illegal tampering with emission systems


Dear Stephen


Thanks for your e-mail.


Regulation 61A of the Road Vehicles (Construction and Use) Regulations 1986, as amended, makes it an offence for a person to use, or cause or permit to be

used, on a road a motor vehicle if the motor vehicle does not comply with such limit values as may apply to it by virtue of an emissions directive and especially if the failure to meet the limit values results from an alteration to the propulsion unit or exhaust system of the motor vehicle.


The Department for Transport is responsible for transposing Directive 2010/48/EU into UK law.  I am forwarding to the relevant people to confirm progress on transposition.  They should contact you in due course.


I hope this helps.




I Mohammed Farooq I Legislation Manager I Vehicle Certification Agency I 1 Eastgate Office Centre I Eastgate Road I BRISTOL I BS5 6XX I Tel +44 (0) 117 952 4119 I



From: Stephen [mailto:owlsmoor -at- googlemail.com] Sent: 27 January 2012 19:15 To: Mohammed Farooq Subject: Re: query: illegal tampering with emission systems




The Problem with your definition is that no-one ever knows for sure if tampered vehicles will comply with type approval emission levels or not, and few outfits would have the facilities or inclination to determine if they would comply!  However the bolded terms in my original Email to you of 2010/48/EU (see below) specify no limit values, only ‘absent’, ‘modified’ or ‘obviously defective’ which makes the illegality of this practice in little doubt.  

This was the loophole which tampering outfitters were using.  Their line was is that it would probably pass, and VOSA wasn’t bothered anyway.  They knew the MOT test was insufficient to determine conformance to type approval or COP. This new regulation seems to place the onus on them to resubmit vehicles for type approval if anything is removed or tampered with, which of course is unlikely to happen since this would be uneconomic.


Have I interpreted this change correctly? Bob





Dear Stephen


I have forwarded your enquiry to Bob Moran (bob.moran@dft.gsi.gov.uk) at the Department for Transport, as he is responsible for policy in this area.  From a type approval point of view, it wouldn't be possible to type approve a single vehicle.




I Mohammed Farooq I Legislation Manager I Vehicle Certification Agency I 1 Eastgate Office Centre I Eastgate Road I BRISTOL I BS5 6XX I Tel +44 (0) 117 952 4119 I




Did you ever receive this Email forwarded from Mohammed?  It’s only fair you should have every chance to reply!   However if I don’t hear within 2 weeks I will assume you are disinterested.




Of course no answer was ever received


It appears obvious that the de-facto law of the country is primarily to support businesses, whilst turning a blind eye to enforcement of regulations, and allowing the public to pay for the wider consequences in terms of their health.








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