Que signifie le code P2002?
D'une part, les moteurs diesel offrent un couple et une économie de carburant supérieurs à ceux des moteurs à essence. D'autre part, le carburant lui-même a tendance à produire davantage de PM 2,5 et de PM 10 ou «suie» (particules de moins de 2,5 µm et de 10 µm), ce qui est dangereux pour la santé humaine et l'atmosphère. La technologie des moteurs diesel modernes et le raffinage du carburant diesel ont réussi à éliminer une grande partie de ces émissions, mais il existe encore certaines circonstances dans lesquelles plus de particules seront générées, généralement lorsque le moteur ne tourne pas aussi chaud, comme lors de courts trajets ou lors de et-aller le trafic.
[Vous devez être inscrit et connecté pour voir cette image]The diesel particulate filter (DPF) captures PM emissions that are generated while the vehicle is driven in low-load conditions, storing them until they can be burned off. When the vehicle is driven in high-load conditions, such as up hills or on long trips, the ECM (engine control module) will command additional fuel injection, which increases DPF temperatures to 450 °C to 600 °C (840 °F to 1,112 °F), enough to completely oxidize stored PM emissions, clearing the filter without releasing harmful PM emissions to the atmosphere. This process is called DPF regeneration or “regen” and typically occurs automatically every 250 to 500 miles.
The ECM uses a differential pressure sensor (DPS) to measure the effectiveness and capacity of the DPF. Simply speaking, the DPS measures the difference in pressure before and after the DPF. A clean filter doesn’t provide much resistance to the exhaust close, and the DPS measures little to no pressure differential. As the DPF collects PM emissions, resistance to exhaust flow gradually increases, effecting a gradual increase in pressure differential. Depending on the vehicle, a certain DPS threshold may trigger a DPF regen cycle, but only if conditions are right. Some vehicles may trigger a DPF regen cycle around 15% capacity, for example.