Evaporative Emission Purge Solenoid Valve Leak Test

If the Q12 Evaporative Emission Purge Solenoid Valve does not seal properly, fuel vapors could enter the engine at an undesired time, causing driveability concerns. The ECM tests for this by commanding the G58 Evaporative Emission Purge Pump, the Q12 Evaporative Emission Purge Solenoid Valve OFF/Closed and the Q13 Evaporative Emission Canister Vent Solenoid Valve ON/Closed which seals the system. With the engine running, the ECM then monitors the B150 Fuel Tank Pressure Sensor for an increase in vacuum. The ECM will set a DTC if a vacuum develops in the tank under these test conditions.