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DPF Regeneration

Since 2009 exhaust emissions standards for new vehicles have required fitment of a DPF (Diesel Particulate Filter) to reduce carbon footprint. So, many vehicles from '09 plates onwards effectively will have one fitted.  There are several benefits to having this kit fitted.

The Effects of DPF Regeneration 

It reduces diesel particle soot into the atmosphere. However, lack of motorway or long distance driving can cause this part to block. So it is recommended that changes to driving style to maintain the system's functionality. This can be very expensive.

The process of DPF Regeneration 

To maintain your vehicle's performance, Eurofit Autocentres can perform an active DPF regeneration. This process involves burning the blocked soot at a high temperature to leave only a tiny ash residue.

When the soot loading in the filter reaches a set limit (about 46%) the vehicle's ECU will initiate post combustion fuel injection to increase the exhaust temperature & trigger regeneration. If you undertake a lot of short journeys or stop & start trips, the process will not complete & trigger the engine management light.

It should be possible to complete a regeneration cycle & clear the warning light by driving for about 10 minutes,  at speeds greater than 40mph. 

Unsuccessful DPF Regeneration and how to prevent it 

If the regeneration is unsuccessful due to an insufficient driving cycle, the extra fuel injected into the cylinders will not burn & will drain into the sump.  As a result, oil quality will deteriorate & the level will rise.  Most DPF equipped engines will have an oil quality/viscosity sensor but it is important that you check that the oil level does not increase above the maximum level on the dipstick, as diesel engines can run on their own oil if the level is excessive – often to the point of destruction.

If you ignore the DPF warning light & keep driving in a relatively slow, stop/start pattern, soot loading will continue to build up until around 75% when you can expect to see other dashboard warning lights come on too. At this point, driving at speed alone will not be enough & you will need to take the car to a dealer for 'forced' regeneration.

Forced regeneration

Forced regeneration  is required where `active` regeneration criteria have not been met or where soot levels have increased within the DPF to a point where normal regeneration cannot be performed: typically around 70% soot loading.  At this point the vehicle will enter a 'restricted performance' mode to prevent further damage.  If left the soot loading will keep rising. 

At this level of soot loading, a diagnostic tool must be used to force regeneration. Above around 85% soot loading, regeneration can no longer be performed on the vehicle & the DPF will need removing to be cleaned or replaced.

What can prevent normal regeneration taking place?
  • Frequent short journeys where the engine does not reach normal operating temperature
  • Wrong oil type – DPF equipped cars require low ash, low sulphur engine oils
  • A problem with the inlet, fuel or Exhaust Gas Recirculation (EGR) system causing incomplete combustion will increase soot loading.
  • A warning light on or diagnostic trouble code logged in the engine management system, may prevent active or catalyst regeneration
  • Low fuel level will prevent active regeneration taking place. As a general rule ¼ tank is required
  • Oil counter/service interval – exceeding the service interval may prevent regeneration
  • Additive tank low or empty – if the vehicle uses Eolys™ additive a low level may prevent regeneration.

If you continue to ignore warnings & soot loading keeps increasing, then the car won’t run properly & the most likely outcome will be that you will have to get a replacement DPF.

The ash residue which remains after successful regeneration cannot be removed & will eventually fill the filter.  DPFs are designed to last in excess of 100,000 miles but if the drivers fail to operate the vehicle correctly, it will fail a lot earlier.

Some models, across a wide range of manufacturers, use a different type of DPF which relies on a fuel additive (Eolys™ fluid) containing Cerium (III) Oxide. These are usually found at fuel stations. The additive is stored in a separate tank, on the vehicle usually next to the fuel tank & is automatically mixed with the fuel whenever you fill up.

DPF removal is illegal

DPFs are factory fitted to meet European standards to reduce carbon footrpint. 

According to the Department for Transport, it is an offence to use a vehicle which has been modified or had its DPF removed. This makes the vehicle illegal to drive on public roads, invalidating your insurance and MOT.

How can Eurofit Autocentres help?

At Eurofit Autocentres we are able to diagnose & regenerate Diesel Particulate Filters (DPFs). The DPF helps to reduce the amount of soot that is released into the atmosphere by diesel vehicles.  A manual regeneration maybe required if your vehicle has suffered from a DPF blockage or the DPF warning light is active.

Common exhaust faults include: blowing, hole in exhausts, catalytic convertor faults, DPF light on dashboard, corrosion, internal breaking of exhaust fibres & limp mode. 

Eurofit Autocentres advise booking a diagnostic first if you suffer from any of the common faults, as on occassions mechanical or electrical components can cause similar symptoms.

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