Stuart Still, Technical Trainer with European Exhausts and Catalysts (EEC) explains how and why Diesel Particulate Filters (DPF) fail and the procedures involved on diagnosing and rectifying faults.
On my visits to various customers I made enquiries about the general demand for DPF’s, and I was staggered at the lack of DPF knowledge, especially the procedure regarding installation.
The majority of the answers were: “We regard it as a main dealer only product“ or “We don’t want to get involved with DPF’s as it is
all too complicated” and even “We need specialist diagnostic tools”.
EEC decided to eliminate one of these major objections. We contacted a diagnostics tool company with a similar business outlook to ours, and discussed the opportunity of becoming our partners in a venture to create a specialised hand held DPF diagnostic tool.
After many months of intense discussions and hard work collating all of the data required to deliver an easy to use hand held bespoke DPF tool, I must say that we are extremely excited with the end result.
The “EEC DPF Reset Tool” is now available throughout the EEC customer network.
Why would you need one?
The DPF is only a filter which removes particulates, soot/carbon from the exhaust gases.
The main dealers account for the majority of the DPF’s fitted within our market place.
A DPF is a serviceable item that needs to be replaced at the end if its life. This varies with each vehicle manufacturer from Ford at 75,000 miles to BMW at 150,000. The OE manufacturers’ warranty does not cover over filling, as they are regarded in the same way as oil, fuel, or air filters. The warranty only covers mechanical failure.
The aftermarket is missing out on an opportunity to increase their sales and profit margin! DPF’s are a high ticket product!
There seems to be some confusion as to why they could over fill and how to diagnose faults. This is where the EEC DPF tool becomes a necessity. It is extremely unusual that a DPF will fail on its own! The problems are usually upstream of the DPF or due to an issue with the DPF system.
The majority of vehicle manufacturers have the same warning light sequence, but always check the vehicle’s own handbook to be safe. If the DPF light comes on this means regenerate is needed. Once again, read the hand book for instructions. For example, ‘Drive for 20 minutes @ a constant 65mph’.
If the DPF is not regenerated at this stage and fills to over 90 per cent or 45 grams, the DPF will need replacing. This is not covered under warranty. If the coil and engine management light is on with loss of power, limp home mode will engage with a maximum of 3000 RPM. The fault code will read ‘DPF soot loading too high’. Forced regenerate is now required.
In order to carry out a forced DPF regeneration using the EEC DPF diagnostic tool you need to ensure the vehicle is parked outside, in park/neutral, the hand brake is on, engine warm, with at least a quarter tank of fuel, and that there are no fault codes stored (step by step guide supplied with the reset /regenerate tool).
If the engine management light comes on first, followed by the DPF light, it indicates an issue within the DPF system, for example temperature, pressure, sensors etc. (use the EEC DPF tool to identify).
Check pressure sensors. There could be a build up of water. Examine pressure pipes for damage. They must be clean or could freeze in extreme temperatures due to water build up. Check that the EGR system is working correctly. Check that the vehicle has the correct spec engine oil. Check the additive (active system) Eolys / Cerine.
When the DPF filter load reaches a pre-determined level, the ECU activates a regeneration process to increase the DPF temperature to over 5500. The engine is set to run in a certain specific way and can inject up to eight times more fuel per stroke to produce a high amount of NO2, which will help oxidize the particulates, increasing the temperature as the exhaust gases pass through the catalytic converter.
It is advisable to check the oil for diesel contamination as a result of constant DPF regeneration, if this occurs you must carry out a full oil change and replace the oil filter.
The ECU must be re-adapted when replacing the DPF and when topping up the fuel additive Eolys.
The DPF will not regenerate if the engine management light is on, or there is a faulty EGR valve. Regeneration will not take place, if there is less than 20 litres of fuel in the fuel tank, if the fuel light is on or the engine management light is illuminated.
For more information on the EEC range contact National Autoparts or KC Products.