DPF Ireland

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DPF Fault Finder

DPF Fault Finder

A diesel particulate filter, also known as DPF, is designed to eliminate soot or diesel particulate matter from a diesel engine’s exhaust gas. These filters can sometimes block prematurely, and oftentimes simply cleaning or replacing the DPF will solve the problem. In most situations, a DPF requires to be professionally cleaned or replaced around 80,000 miles . It is advised that if your vehicle is coming up to the 80K mark and to avoid experiencing a more serious DPF problem , give us a call and have your DPF professionally cleaned by our highly trained technicians.


How Does a DPF Work?

A diesel particulate filter, also known as DPF , is essentially a trapping mechanism that captures small particulates of soot as it travels through the exhaust system of the car and prevents it from being released into the air. All DPF filters require cleaning on a regular basis , a process called regeneration. This process implies the burning of the soot of the filter at very high temperatures, which leaves a small residue of ash behind.

All diesel engines produce these small particulates while operating. This type of filter has been in use for almost three decades, but modern DPFs have been added as a default on many diesel vehicles since 2009.

Modern diesel cars and vans use one of two forms of regeneration: passive and active. The passive regeneration process is carried out automatically when you drive your vehicle, at higher speeds , on faster roads or motorways. An active form of regeneration is available for cars that rarely make this kind of journey. For this process, the system starts a post combustion process of fuel – injection when the ECU senses that the filter has gone over a specified limit, such as 50% of its capacity.


What Causes a Blocked DPF?

Multiple things may cause a blocked DPF, but the most common of them include a faulty EGR (Exhaust Gas Recirculation) , using the wrong oil, a faulty turbo charger, or faulty fuel – injectors. Another very common reason for blocked DPFs is the tendency of many drivers to drive only short distances. Urban driving requires a lot of starts and stops , which makes it impossible to replicate the conditions required for passive DPF regeneration.


What Does It Mean When DPF Light is On?

A DPF warning light means that the filter continues to collect soot and that the need for cleaning is imminent. When the filter reaches about 75%, you may notice warning lights appearing on the dashboard of your vehicle , at this point the car’s performance will be restricted. If you delay the cleaning of the filter up to this point, you will find that the unblocking process is going to be more complicated, and that in most cases it will need to be carried out by a mechanic. If a DPF filter reaches a capacity of about 85%, you may need to replace it altogether or at least remove it for manual cleaning.


Diagnosing a Problem with a Blocked or Clogged DPF

Most DPF problems come with their own fault codes, so you can easily determine the kind of fault you are dealing with.In order for DPF regeneration to work correctly, you must ensure that there is enough fuel in the tank at all times. This means that you should maintain your tank at least ¼ full. Moreover, the soot content needs to be under 45 percent on average in order for passive regeneration to take place.

An unresolved fault when the light is on will generally prevent the regeneration process from starting, which means the DPF will be blocked. Below are some of the diagnostic checks you need to be aware of before installing a new DPF or diagnosing a fault with an existing one.

  1. Oil Level – when the oil level is high, this is a sign that fuel from failed regeneration attempts has contaminated it. In this situation, an oil change will be necessary. You will also need to check whether the exact type of low ash oil has been used.
  1. DPF Pressure Pipes and Sensors – make sure all the pipes are not suffering any blockage or any other type of damage and that the pressure sensor is working as it should.
  1. Fuel Additive – make sure the level of fuel additive is right, and fill the tank as required. Most manufacturers offer detailed information about this procedure and the technical documentation.
  1. Further Checks – there are multiple other items that require checking, which include , the engine and turbo wear, airflow meters, injectors, and the ECU.

How to Clear a Blocked DPF

Our recommendation is to take your vehicle to a qualified DPF specialist such as ourselves. The handbook you received with your vehicle will generally have a section in relation to DPF , and the event of the warning light being on. Quite often it says in the handbook to take your vehicle to a trusted garage if you aren’t mechanically trained to diagnose and fix the fault. As a short term solution until you get your vehicle booked in with a mechanic you could try the following procedure to clear the DPF as most engines require roughly the same process. – Start by warming up the engine to the operating temperature, and then drive for about 15 minutes at constant speed on a motorway. Your aim should be to keep the revs above 2000 rpm for the entire period. The heat generated in this way will clean the DPF filter and the regeneration cycle of the vehicle will kick in.

If you notice that your engine is misfiring, you should not attempt high revs, and try to build up the heat slowly on a longer run instead. As a rule of thumb, you should try to avoid short journeys where the engine does not fully warm up in order to prevent further DPF blockages. You should keep in mind that in the majority of cases there is only a relatively short time period before the filter becomes partially blocked and the car going into limp mode.


Always Check with an Expert

Reading the relevant section of the vehicle handbook is important to get a general understanding of what the problem could be. But when it comes to DPF faults , only a qualified technician that uses the latest technology should be anywhere near your vehicle. By doing so, you can rest easy that the job will be done professionally , and in a way that will increase the efficiency and lifespan of your DPF.

Get in contact with us now to get your DPF professionally cleaned.