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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1348 (Engine Control System (Introduction) -- 1.8L (LNK)) >> Description and Operation >> Evaporative Emission (EVAP) Control System Description >> EVAP Purge Valve Operation

EVAP Purge Valve Operation

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

If the EVAP purge valve does not seal properly, fuel vapors could enter the engine at an undesired time, causing driveability concerns. The PCM tests for this by commanding the vent valve closed and the pressure switching valve open causing a vacuum, in the entire EVAP system. The PCM continues to operate the purge valve until the vacuum is lowered to a specific point, at which time the purge valve is commanded closed. The PCM monitors the fuel tank pressure (FTP) sensor. If the PCM does not detect a drop in vacuum, or the vacuum increased beyond the specified limit, for two consecutive trips, the MIL will be illuminated, and a DTC P0441 will set.

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