Purge Flow Sensor: Description and Operation

Description:

EVAP PURGE VACUUM SWITCH
The Evaporative Emissions (EVAP) System Purge Vacuum Switch is used by the PCM to monitor EVAP canister purge solenoid operation and purge system integrity. The EVAP Purge Vacuum Switch should be closed to ground with no vacuum present (0% EVAP Purge Pulse Width Modulation [PWM]). With EVAP Purge PWM at 25% or greater, the EVAP Purge Vacuum Switch should open.

CIRCUIT MALFUNCTIONS
An incorrect EVAP Purge system flow should set a Diagnostic Trouble Code (DTC) P0441. A continuous purge condition with no purge commanded by the PCM should set a DTC P1441. Refer to Computers and Control Systems / System Diagnosis / Procedures / Diagnostic Tables for DTC Tables.