What is a DPF?
A Diesel Particulate Filter (DPF) is a device fitted on the exhaust system of all new diesel-powered vehicles sold since 2009, it’s designed to remove soot and diesel particulate matter from exhaust gasses enabling them to pass increasingly difficult emissions legislation.
How does a DPF work?
A DPF works by trapping soot as it passes through the exhaust system to stop it from being released into the atmosphere. As with all filters, the Diesel particulate filter needs to be cleaned regularly, this is achieved through a process called regeneration. There are three ways a regeneration can take place, passive, active and forced.
DPF Regeneration.
Passive regeneration takes place automatically when the exhaust reaches a high enough temperature usually achieved on motorway type runs. However, many vehicles don’t often get this type of journey so this is when active regeneration takes place. Active regeneration takes place when soot levels in your DPF reach about 45%.
The ECU will make small adjustments to fuel injection timing to increase temperatures in the exhaust. This increase in exhaust temperature will start the regeneration process burning away the soot in the DPF. A Forced regeneration is achieved using a specialist diagnostic tool and providing certain parameters are met you can initiate a static regeneration that usually takes about 30 minutes with the vehicle stationary.
What causes a DPF to fail?
It’s a common misconception that driver fault is the prime cause of DPF faults, most of the time there is an underlying fault that causes the DPF to start blocking and unable to regenerate.
These faults can be as simple as an engine management fault preventing an active regeneration taking place, to a mechanical problem such as a split pressure pipe causing incorrect readings. Any garage attempting to repair any DPF faults should always start with an engine diagnostic.
What can I do to prevent my DPF from blocking?
There are four things you can do to help prevent any issues with your DPF. The first is making sure the car is well maintained and the correct specification of oil is used when servicing.
Second is to make sure you get any engine management lights checked out as soon as possible as these could prevent an active regeneration taking place. Third is to try and assist your DPF by taking occasional motorway journeys to get your exhaust up to the required temperatures and finally don’t change gear too soon, as
Third is to try and assist your DPF by taking occasional motorway journeys to get your exhaust up to the required temperatures.
Finally, don’t change gear too soon, as tempting as it may be to try and save fuel, laboring the engine in the wrong gear is very bad for diesel engines.
Do I need to replace the DPF if it fails?
Despite what franchise dealerships will tell you, you do not need to replace your DPF if it fails. There are multiple and far cheaper solutions available to you no matter how blocked your current DPF is.(unless it is damaged within)
How much does it cost to replace a DPF?
To replace a diesel particulate filter before attempting to clean it can easily cost in excess of £1500.
