What is a Diesel Particulate Filter?

Diesel Particulate Filters, also known as a DPF, are designed to reduce soot and carbon from exhaust gases, thereby lowering your vehicle’s emissions in order to meet UK & European legislation – this in turn, also reduces your vehicle tax.

In short, the DPF is designed to minimise the level of harmful particles that are released from Diesel Vehicle Exhaust systems.

How does a DPF work?

A DPF simply gathers particles of soot in the exhaust system – as you would expect with any filter though, they do need to be emptied and cleaned regularly to keep maintain the vehicle and engine performance. This is also known as ‘regeneration’.

There are different types of regeneration. These are called passive, active and forced regeneration.

Passive regeneration

With passive regeneration, the DPF cleans itself by heating up and burning off the accumulated particles. This process requires a high exhaust temperature, which can be achieved by driving normally on long journeys.

Active regeneration

This is when additional fuel is injected automatically as part of the ECU. Once the filter reaches its limit, the ECU burns more fuel to clean the DPF by burning off the soot.

Usually, the filters limit is around 45% capacity.

Forced regeneration

This is when you take your vehicle to a garage to have your DPF cleaned and remove and trapped soot. Sometimes, this is required if you are making regular short journeys as its unlikely the exhaust or DPF will reach a temperature where it can regenerate itself.

If there is an issue with your DPF, the driver is usually notified with a warning light on your vehicle’s dashboard.

What to do if the DPF warning light appears

If your DPF warning light appears, it means your DPF needs help with regeneration. Usually, this can be resolved by driving the vehicle at around 50mph for around 15 minutes, while keeping the engine at 2500RPM to 3500RPM. Please check your vehicle’s handbook for more information as this may vary between vehicles.

Once the DPF has successfully regenerated, the warning light will turn off.

DO NOT ignore a DPF warning – this can result in a loss of power and cause serious mechanical issues that are not covered by the vehicle warranty. It will also cause harmful exhaust emissions to remain trapped within your engine.