Circuit Description

To reduce HC emissions, evaporated fuel from fuel tank is routed through charcoal canister to the intake chamber 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:

• EVAP VSV.
• Open or shorted EVAP VSV circuit.
• Open or shorted vapor pressure sensor VSV circuit.
• Vapor pressure sensor VSV.
• Open or shorted vapor pressure sensor circuit.
• Vapor pressure sensor.
• Disconnected, damaged or blocked vacuum hose.
• Charcoal canister damaged.