Evaporative Emission (EVAP) Control System Diagnosis

ORVR Fuel System
Always start with the Powertrain On-Board Diagnostic (OBD) system check. This will reduce diagnostic time and prevent unnecessary parts replacement. The Enhanced Evaporative Emission (EVAP) control system diagnosis is covered in the following DTCs:
^ DTC P0440 Evaporative Emission ([1][2]EVAP) System
^ DTC P0443 Evaporative Emission (EVAP) Purge Solenoid Control Circuit
^ DTC P0446 Evaporative Emission ([1][2]EVAP) Vent Solenoid Control Circuit
^ DTC P0450 Fuel Tank Pressure Sensor Circuit
^ DTC P0455 Evaporative Emission ([1][2]EVAP) System Leak Detected

System Inspection and Cleaning

Important: Disconnect the hoses/pipes from the EVAP canister and the [1][2]EVAP purge valve before applying compressed nitrogen.

Disconnect the vacuum source line at the purge valve and the manifold vacuum source. Remove the [1][2]EVAP purge valve. Disconnect the purge line at the canister. Inspect all of the hoses/pipes/components for contamination. If a component is malfunctioning due to contamination, the component must be replaced. Contaminated of the hoses/pipes should be blown out with compressed nitrogen from the EVAP pressure/purge cart J 41413.

If carbon contamination of the system is evident, replace EVAP canister/fuel tank.