What else should I be aware of?

motorway-trafficIt is often said that you should “go for a blast” down the motorway to clear the DPF. Please note this is only partially true. If the DPF is blocked beyond the capacity for regeneration or blocked due to Ash residue, you will do more harm to your engine.

Clear a Blocked FilterThere are many DPF cleaning additives available promising a magic cure for DPF. We have yet to find one that will clear a blocked filter and will certainly not clear an Ash blocked filter. Some products can however be useful in keeping a functional DPF in good health.

Blocked Flat DPF cut openDPF units are closely linked with other engine components e.g. Turbo, Injectors, EGR, FAP, Sensors etc, if these parts do not function properly they can help to block the DPF, similarly a blocked DPF can damage these components due to excess back pressure and soot. DPF units are located close to the Turbo, if the turbo oil seals are leaking oil into the exhaust, it can quickly  block the DPF. If a blocked DPF is not attended to for a long time the excess back pressure can damage the turbo oil seals and make the problem worse.

dpf and scr diagramSome PSA engines fitted to Peugeot, Renault, Ford, Volvo and Nissan have an on board Fuel Additive System (FAP) connected to the DPF to help regeneration. It is important to maintain this system and keep it topped up with the additive, if not it will block the DPF. In our experience this is often neglected, even by main dealers. If the FAP system is no longer required we can disable the system on request.

Dash LightsNewer vehicles have a dedicated DPF or Anti-Pollution warning light which is great, however many will just show an Engine light or symbol. An engine light can show for many different faults so it is important to check by electronic diagnostics why the light is on as soon as possible. On some occassions we have seen vehicles with severly blocked DPF but with no warning lights showing at all. It is not advisable to simply get the light turned off without investigation or repair as the underlying fault will cause more serious problems.

Appropriate RecalibrationDPF work is complex and should only be carried out by experienced professionals with the correct specialist equipment. It cannot be done properly by a mobile service. All work on a DPF (regen, replacement, clean etc) has to be completed with the appropriate recalibration or reset on the vehicle ECU. It is not possible to simply delete the DPF electronically, this can cause serious problems and even fire risk. Similarly it is not possible to remove the DPF unit from the vehicle without recalibration work on the ECU.

It is our experience that many garages including main dealers are not knowledgeable in DPF problems and related issues. We often see customers after they have spent a lot of money on the wrong fixes as the DPF fault was not correctly diagnosed. We take the policy to clear all peripheral faults showing, fix the DPF problems first then see if the peripheral faults reappear again, in most cases they do not because they were not faulty in the first place.

DPF Cut AwayDPF units consist of a central core made from a ceramic type of material which is coated with catalyst minerals like Palladium and silver nitrate. Original manufacturer parts (OE) usually use better materials like Silicone Carbide (SiC) and better coatings whereas aftermarket parts usually use cheaper materials like Cordierite (C) and coatings that range from good to none at all. Without a catalyst coating a DPF will not regenerate, hence will block very quickly. It is therefore important to choose a replacement DPF carefully. A well cleaned DPF will generally out perform a cheaper aftermarket item.

Diesel Particulate Filters were designed with good intent to reduce emissions and most imporatntly reduce harmful PM10 particles from the environment. In theory a DPF would trap soot in urban areas and then regenerate on the open road, unfortunately this does not always work well leading to expensive repairs. Many things dictate how soon a DPF will block up e.g vehicle usage, size of engine, manual or auto gearbox, driving style, quality of fuel and engine oil used, routine DPF maintenence etc. A diesel vehicle used for its purpose and maintained well will give years of trouble free motoring, a DPF does not necessarily mean “problems”.

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