Purge Flow Sensor: Description and Operation

PURPOSE
The Evaporative Emissions (EVAP) Purge Flow (PF) sensor is used to monitor the EVAP Canister Purge (CP) valve operation during the OBD II EVAP test.

OPERATION
The PF sensor monitors the vapor flow through the EVAP canister purge valve and changes the PF valve input signal to the PCM based on flow or no flow conditions.

The PCM monitors this signal and gives an output signal to the EVAP CP valve based on the flow conditions.