Diesel Particulate Filters (DPF)
Changes to car emission legislation introduced in September this year (the Euro 5 standard), will make Diesel Particulate Filters extremely common in new vehicles. The goal of the Euro 5 standard it to make an 80% reduction in particulates or soot coming from diesel vehicles.
How do they work? - Diesel Particulate filters (DPF) catch particles of soot in the exhaust. As with any filter they do require regular emptying, for a DPF this process is called 'regeneration' – the accumulated soot is burnt off at high temperatures to leave only a tiny ash residue. There are 2 types of regeneration passive and active.
Passive regeneration - Passive regeneration is an automatic process, on motorway style journeys where the exhaust temperature is high. Most cars don't get this sort of use, so manufacturers have to design-in 'active' regeneration where the vehicle ECU takes control of the process.
Active regeneration - When the amount of soot in the filter reaches a set limit around 45%, the ECU can make small adjustments to the fuel injection timing to increase the exhaust temperature and initiate regeneration. If the journeys are very short the regeneration may not complete and the warning light will illuminate to indicate that the DPF is partially blocked. A complete regeneration should be possible by simply driving for 10 minutes or so at speeds greater than 40mph.
If the customer ignores the light and continues in a town driving style, the soot amounts will continue to build up until around 75% when you can expect to see other warning lights illuminate. At this point driving at speed alone will not be sufficient and the car will have to come in for regeneration.
Expensive repairs - Should warnings still be ignored and soot builds up further then the most likely outcome will be a new DPF costing around £1000. If the car is used mainly for town based driving, it may be better to use a petrol car rather than have the hassle of failed DPF regeneration.
DPF additives - The most common type of DPF features a catalytic converter and is located very close to the engine where exhaust gases will still be relatively hot so that passive regeneration is still possible.
Some vehicle manufacturers don't have the required space close to the engine, so they use a different type of DPF which relies on a fuel additive to lower the ignition temperature of the soot particles so that the DPF can be located further from the engine.
The additive is stored in a separate tank and is automatically mixed with the fuel whenever you fill up. Small quantities of additive are required though, so a litre of additive should treat around 2800 litres of fuel, enough to cover 25,000 miles at 40mpg. With this type of DPF regeneration will be initiated by the ECU every 300 miles or so depending on vehicle use and will take 5 to 10 minutes to complete.
Failures - There are already cases where these systems fail to regenerate, even on cars used mainly on motorways. Some cars have a very high sixth gear, and the engine RPM and exhaust temperature is not high enough for regeneration.
Check the handbook - If you get a car in with DPF problems check the handbook to see exactly what actions to take if the warning light illuminates and how, if at all, their driving style may need to be adjusted to ensure maximum DPF efficiency and life.

Mechanics Tools and Equipment Tax Rebates
If you have worked as a mechanic in the last 6 years or are working as a mechanic at the moment and have bought tools or equipment that you need to carry out your job you may be due a tax rebate.
If you have not been fully reimbursed by your employer then you can secure a mechanics tax rebate that can go back up to 6 years.
What can you do - We offer a hassle free service that verifies the forms and collects the required information, we then file the claims with HMRC.
What we need - Collect receipts for your equipment - we will need receipts for the equipment that you have bought. Your supplier should be able to provide you with a print out going back a few years, If you prefer, we can deal with your tool rep to get the receipts.
Charges - There is a 25% charge (+VAT) of any rebate, but only if the claim is successful.
We work on the no win no fee basis!
You can claim back relief yourself - You can claim directly and cut out the cost of the service fee, to do this contact the HMRC with your N.I. number and request form P87.
For more information click visit here: Mechanics Tax Rebate
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