Imagine driving along, perhaps with your children in the back of the car, when the vehicle in front suddenly releases a plume of Mustard Gas directly into you path. It would be a horrifying and potentially deadly experience. Yet thousands of Irish motorists do the equivalent on a daily basis, while many in the Irish motor trade seem unaware of their part in letting this happen.

The reason behind this is because for many motorists and garages, the so called "smart” solution to the problem of a blocked DPF is to simply remove it. They tend to take the attitude that, "The customer saves money and it’s legal, so what harm can it do?” However, the cold hard facts are that a car that has the DPF removed is throwing out completely untreated emissions. Diesel emissions are classified by the World Health Organisations as a Class 1 carcinogen. This means it is a substance or exposure that can lead to cancer, like for example, Asbestos, Formaldehyde, Plutonium and Mustard Gas.

Diesel Particulate Matter (DPM) is more dangerous than gas emissions, because it contains microscopic particles that significantly increase the risk of cardiovascular, cardiopulmonary and respiratory disease and lung cancer. In the US, the State of California identified that around 70% of the risks associated with air-related cancer causes, could be attributed to diesel emissions. In the UK, 29,000 early deaths each year are attributed to air pollution with particulate matter being a major contributor. The UK Committee on the Medical Effects of Air Pollutants in 2008 concluded that, the average reduction in life expectancy as a result of airborne particulate matter across the population was 6 months. The fact is there is there is no "safe” limit for exposure to fine particulate matter.

These compelling health reasons should be enough to make any respectable business shy away from DPF removal, but there are also other practical considerations. Often a problematic DPF is only a symptom of a wider issue, or problems with injectors, throttle bodies, EGR valves, MAP sensors, MAF sensor and IAT sensors. So take the DPF out and the chances are the unhappy customer keeps coming back. Removal of course invalidates any warranties and the necessary recoding always has some inherent risk. The overall pictures is that if a vehicle has a DPF it’s engine and emissions management system has been designed  with the DPF in mind. Take it away and it is only natural for performance issues and engine and emissions faults to develop. 

This is illustrated well by Automotive Trainer Steve Carter, who was one of the first to highlight DPF concerns. He comments, "Many Citroen Peugeot engines since 2O15, which are also used on other makes, have Selective Catalytic Reduction or SCR AdBlue systems. If you were to remove the DPF from one of these vehicles, it would generate all kinds of SCR fault codes and could even mean a complete system shut down, so the car won’t start.”

The question of legality is also more than a little clouded. Under Irish road traffic legislation, it is an offence to drive a vehicle that has been modified to a point where it fails to meet emissions standards. So in strict terms the DPF removal is legal, but driving the car is illegal. This change in emission standards could also have road tax implications and modification could potentially invalidate insurance in the event of discovery after an accident. The technician should make the customer aware of the pollutant, legal, & performance issues, it’s an opportunity to upsell, but ultimately it’s a consumer choice. 

However, most people seem satisfied if a car passes its NCT and with only a circumspect visual inspection, this can be easily done. However, some more notes of caution from Steve Carter should be considered. He says, "In the UK some garages have been offering removal services, but the changes to the MOT have moved the goal posts again. They will now find that having provided a quick fix and taken out the filter to pass the MOT last time, next time around the car will fail and the customer will face a very expensive bill to reinstate it.” He adds, "In other countries the tide has turned even further, for example in Germany, a garage advertising DPF removal would be instantly shut down by Trading Standards, so I think it is only logical for Ireland to go the same way.” 

What are the alternatives to DPF removal? 

The aftermarket has not been slow to innovate in this area and there is now a wide range of preventative maintenance and cleaning products, as well as cleaning equipment and specialist cleaning services. 

Prevention is always better than cure, so the use of certain additives is wise to keep DPFs operating well and aid regeneration. Offering these additives also has great business potential. For more problematic DPF’s, there is the possibility of forced regeneration and using cleaning additives. The next set up in the process is to flush and clean the DPF in situ, with specialist fluids and equipment.  

These processes effectively remove the build up of soot in the DPF. However, when the soot is burnt off, it leaves behind even tinier particles of ash which are incombustible. It is generally the ash that causes serious clogging, often building up to a crucial level at somewhere over 80,000 miles, depending on the use cycle. At this stage a different approach is required. The temptation is to take out the core and clean it with an air hose of chemicals. The residue ash is actually the most lethal element in the DPF so garages need to approach with extreme caution. Handled incorrectly, it can easily become airborne and be inhaled with the potential for huge health issues. Some DPFs also contain Eolys additive, which Steve Carter points out can dissolve lung tissue. 

The workshop has a duty of care to employees on this issue. Adequate personal protection equipment is essential, as is a safe enclosed cleaning process and safe vacuum packing and disposal of the hazardous waste produced. Steve comments, "If  garages don’t act responsibly on this issue now, they genuinely run the risk of future health related legal challenges from employees, just like those in asbestos related industries and the body repair industry, when isocyanates were first introduced without the proper protection.” 

The truth of the matter is that diesel particulate matter is highly dangerous and the less a garage has to come into contact with it the better. Fully automated cleaning machines can provide one answer, or having the DPF professionally cleaned by a specialist DPF cleaning company, is often a convenient and economical solution.  

In Ireland, where diesel popularity remains strong, the DPF issue is not going away anytime soon, so it makes sense for garages to be aware of the issues and to find the best solution not only for themselves and their customers, but also for the protection of the health of everyone around. When the facts on health are so stark, and the many other practical consideration are taken into account by both garages and motorists, DPF removal should never be part of this solution. 

Click HERE to see this story in Autobiz magazine