The Evaporative Emission System (EVΑP) is used to reduce the hydrocarbons emitted into the atmosphere by the fuel system. The EVAP system is designed to store the fuel vapors and dispose of the vapors in the intake manifold when the engine is operating. The Engine Control Module (ECM) controls the flow rate of the vapors disposed to the intake manifold.
Regulations require that the EVAP system be monitored for leak detection and performance. By measuring the system pressure at different points of the system, the ECM detects system leaks,
restrictions or if one of the components of the EVAP system has failed.