Circuit Description

To reduce HC emissions, evaporated fuel from fuel tank is routed through charcoal canister to the intake manifold for combustion in cylinders. ECM changes the EVAP system Vacuum Switching Valve (VSV) duty signal so the intake quantity of HC emissions is appropriate for the driving condition (engine load, engine speed, etc.) after engine is warmed up.

DTC P0441 is set if pressure in charcoal canister does not drop during purge control. DTC P0441 is also set if pressure in charcoal canister is very low compared with atmospheric pressure during purge cut-off. DTC P0446 is set if ECM does not detect continuity between vapor pressure sensor and charcoal canister while vapor pressure sensor VSV is off. DTC P0446 is also set if ECM does not detect continuity between vapor pressure sensor and fuel tank while vapor pressure sensor VSV is off. DTC P0446 is also set if pressure in charcoal canister is maintained at atmospheric pressure after purge cut-off operates. Possible causes are:

• VSV for EVAP system.
• Open or short in VSV circuit for EVAP system.
• Open or short in VSV circuit for vapor pressure sensor.
• Faulty VSV for vapor pressure sensor.
• Open or short in vapor pressure sensor circuit.
• Faulty vapor pressure sensor.
• Disconnected, damaged or blocked vacuum hose.
• Charcoal canister damaged.