What it is and how does it works
The European Community, in order to decrease the emission of soot and polluting particles, has obliged the producers of diesel
vehicles to furnish them of FAP or DPF. Contrarily to a catalytic converter, a FAP / DPF doesn’t allow the gases to freely flow because
its channels are alternatively closed: the gases go out after they have flown through the porous walls and they have left the soot
inside the filter.
The FAP / DPF is thought to collect the soot, and needs to be frequently cleaned in active or passive way to avoid its complete blocking.
Passive cleaning is done during the longest journeys, when the temperature of the FAP / DPF is higher and so the soot naturally
When the soot level takes up to the 45% of the filter volume, the vehicle starts autonomously the active cleaning slightly modifying
the fuel injection, which cause a raise of temperature inside the FAP and the soot burns. Some vehicles (especially Citroën and Peugeot)
use an additive which helps the burning of the soot, so that the FAP can be cleaned also by lower temperatures.
Before the replacement:
It is necessary to solve the possible malfunctions of the vehicle:
1 wrong electronic regulation or wrong balance between air / fuel
2 full the additive (for the FAP)
3 working of all the sensors and integrity of the connection cables
During the replacement:
1 always use new rubber.
2 put the FAP / DPF perfectly in line, to avoid vibrations or abnormal pressures.
3 do not to hit the FAP / DPF with metal hammers or other hard tools which could break the monolith
4 as sealant use silicone and not the normal paste for the exhaust system
5 change the motor oil
6 carefully verify the new emissions to solve immediately eventual problems.
7 update the vehicle computer with the specific diagnostic tools
Are not covered by guarantee all the damages caused by external factors as:
1 monolith braking caused by anomalous vibrations or impacts due to accidents or uneven road surfaces.
2 use of oil which doesn’t comply with the specifications given by the vehicle producer
3 obstruction of the monolith caused by the use of paste instead of using the correct sealant silicone
4 obstruction of the monolith caused by oil or antifreeze liquid contamination