How do DPF’s work?

The use of Diesel Particulate Filters on vehicles means that the days of dirty black smoke pouring out of a diesel engine’s exhaust should be long gone, and strict emissions regulations require diesel engines to be a lot cleaner.

A DPF consists of a honeycomb filter structure encase in a metal shell, similar to a catalytic converter. Connected to the DPF is a differential pressure sensor which, in simple terms, detects how much soot is accumulating in the DPF. Soot from diesel combustion is trapped in microscopic channels which are within the DPF, and the process of regeneration normally removes the soot particulates that have attached to the walls of these channels.

There are 3 types of regeneration – Spontaneous, Dynamic and Service. When the Spontaneous regeneration has not been effective, a Dynamic regeneration is initiated and indicated by the DPF warning light coming on in the vehicle. The vehicle must be run if a Dynamic regeneration is to be completed, and the warning light will flash if it is interrupted. If it does flash, a Service regeneration needs to be performed whereby the DPF is taken to a high temperature by a service engineer to clear the DPF, and it must be initiated using a Scan tool.

If a flashing DPF is ignored, the DPF will need to be cleaned, and if not cleaned, it will need to be replaced.