Small EVAP Leak Test

NOTE: This test may run up to 3 times prior to reporting a failure. A PO442 indicates a small leak anywhere between the fuel fill cap and up to but not including the purge solenoid.

The Small Evaporative Emissions System (EVAP) Leak Test runs immediately following a passing Weak Vacuum Test. While the vacuum is still present in the fuel tank, the vent valve and purge valve are both command closed in order to seal the system. With the system closed, the Control Module monitors the trapped vacuum in the system through the Fuel Tank Pressure Sensor. It the vacuum decay rate is too fast, a small leak is indicated and a Diagnostic Trouble Code (DTC) PO442 is stored. Otherwise DTC P0442 is passed and the Excess Vacuum Test - Stage 2 is run.