UK emissions standards for cars effectively required fitment of a DPF in the exhaust of diesel cars in 2009 when the ‘Euro 5′ standard came into force. Many cars before this time already had one fitted in anticipation of this requirement but its generally accepted that very few diesel cars manufactured before 2006 had a diesel particulate filter fitted.

There are two different types of DPF regeneration that are commonly used. These are active and passive. Which ever your car uses you’ll still have to meet some strict conditions in order for the regeneration to start. It’s usually a combination of engine temperature, speed and RPM. A rule of thumb is that the engine needs to have reached normal operating temperature, you’re travelling at more than 40MPH and the RPM (revs) of your engine is at least 2500 RPM. Depending on how blocked or effective your regeneration will determine how long it needs to be performed.

Active regeneration of the DPF is performed by the ECU triggering a post combustion fuel injection. This increases the temperature in DPF, burning off the soot and particles that build up in the filter. This type of regeneration can cause higher than normal fuel usage.

Passive DPF  regeneration takes place automatically on motorway-type runs when the exhaust temperature is high. Many manufacturers have moved to using active regeneration as many motorists do not often drive prolonged distances at motorway speeds. Passive regeneration often uses a DPF additive (see below).

Forced regeneration is a way of cleaning the DPF using a maintenance process which has been built in by the vehicle manufacturer. This process can only be started by either a main dealer / mechanic with the right tools and access to the vehicles management systems. This process usually involves kicking off a DPF clean cycle in the workshop which runs the car at a high RPM for a considerable period of time. The ECU ensures that this cycle heats up the DPF filter to an extreme temperature, burning off the contents of the filter. It some cases the ECU injects fuel into the post combustion process to achieve these temperatures. In most cases the engine oil will need to be changed as the vehicle will literally “cook” the lubricant.

DPF cleaning is a manual process that removes the soot and diesel particulates from the filter. DPF cleaning is achieved using by utilising ultrasonic cleaning technology in combination with specialist chemicals. This process removes all traces of particulate, returning it back to near new condition.