Car Mechanics (UK)
DIESEL PARTICULATE FILTERS (DPFS)
The function of the DPF is to trap soot particles emitted by the engine and stop them from being expelled into the atmosphere, because they are carcinogenic. We provided a comprehensive overview of how they work in the February 2018 issue of CM.
The DPF empties itself by super-heating the soot, causing it to vaporise, leaving a trace of ash behind. This process is called regeneration and it occurs naturally with high exhaust temperatures, such as those resulting from a high-speed run, or by the engine’s fuel injectors initiating a post-injection on the exhaust stroke, which causes diesel fuel to enter the exhaust system, where it combusts, raising the exhaust temperature within the DPF and burning the soot. This process is initiated automatically by the vehicle’s ECU, where a number or parameters must be met, including the vehicle being driven at constant speed/load conditions.
DPF blockage, however, tends to be symptomatic of other issues. Additionally, the ash, which builds up over time within the DPF, cannot be removed, unless the DPF is taken off the car and cleaned by a specialist. Various companies offer this service by post, or through major motor factors.