Diesel Particulate Filters
The above image shows a blocked Diesel Particulate Filter and increasingly we are cleaning more and more DPF’s (Diesel Particulate filters). These are on virtually every diesel since 2008. Manufacturers have even admitted to be working on PPF (Petrol Particulate filters) to meet future euro emissions regulations.
The diesel particulate filter sits in the exhaust system. It catches bigger soot particles, stores them and later burns them off at a higher temperature, somewhere between 500 to 700 degrees Celsius. This whole process is controlled by the engine management system through it’s computer control unit.
There are companies removing DPF’s to cure management faults with the particulate filter system. This generally results in more problems, leaving only one option, to return the vehicle back to standard. Once a DPF has been removed it can only be replaced at great cost, often in the £1000’s.
Our advice is to fix the fault rather than try to remove the filter. The car has been designed to work with a DPF and often the fix is quick if caught early enough. The car will also fail any future MOT tests should it be obvious to the tester that the DPF has been removed. The danger is leaving the repair too long, as without regenerating, the DPF will have to be specially cleaned or replaced.
Generally the reasons DPF’s block prematurely are either; continuous short journeys, as the DPF needs a longer drive cycle to regenerate, a faulty sensor, faulty software or more commonly incorrect engine oil. Many garages are fitting incorrect oil that blocks the DPF during the combustion process. The car should have a fully synthetic, low ash oil fitted. These are more expensive and so often get substituted by garages to be able to supply a cheaper service.
So I suppose the question is why do garages suggest DPF removal? Well it is generally lack of understanding. If you don’t understand the system, you can’t fix it. So the answer is to remove it in the hope that will fix the fault. With some understanding and the correct equipment DPF faults should be easy to remedy and often not as expensive as people think.