Circuit Description

WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The Evaporative Emission (EVAP) system is used to store fuel vapors as to reduce the amount of unburned fuel from escaping into the atmosphere. The EVAP system consists of the EVAP canister, Fuel Tank Pressure (FTP) sensor, EVAP lines and hoses, EVAP purge solenoid (normally closed), EVAP service port, EVAP vent solenoid (normally open) and fuel tank. The ECM monitors the EVAP system for circuit faults in the EVAP purge solenoid, EVAP vent solenoid and FTP sensor circuits. The ECM also monitors the EVAP system for leaks (between EVAP vent and purge solenoid). When certain conditions have been met, the ECM will perform an EVAP diagnostic test at idle with no vehicle speed, which will require a five consecutive phase ("A", "B", "C", "D" and "E") test. DTC P0442 will set if vacuum decays too quickly during Phase "E" of the EVAP diagnostic system test indicating a small EVAP system leak.