Purge Flow Sensor: Description and Operation

Purge Flow Sensor (PFS):

PURPOSE
The Purge Flow Sensor (PFS) is used to monitor the Canister Purge (CANP) solenoid operation during the OBD II Evaporative Emission Test.

OPERATION
The PFS monitors the vapor flow through the CANP solenoid and changes the PFS input signal to the Powertrain Control Module PCM based on flow or no flow conditions. The PCM monitors this signal and gives an output signal to the CANP solenoid, based on the flow conditions.