Purge Flow Sensor: Description and Operation

EVAP System:

DESCRIPTION
The EVAP 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 PWM). With EVAP Purge Pulse Width Modulation (PWM) at 25% or greater, the EVAP Purge Vacuum Switch should open.

An incorrect EVAP Purge system flow should set a DTC P0441. A continuous purge condition with no purge commanded by the PCM should set a DTC P1442.

LEGEND
(1) EVAP Canister Purge Valve Driver Circuit (6) EVAP Canister
(2)) Throttle Body (7) EVAP Vacuum Switch Signal
(3)) Rollover Valve (8) EVAP Vacuum Switch
(4)) Fuel Cap (9) EVAP Canister Purge Valve
(5)) Fuel Tank (10) Ignition Feed Circuit