P0446 Evaporative Emission Control System Vent Control Circuit Malfunction (notes)

  1. P0446 – EVAP Vent Solenoid Valve Control System –

  2. The Evaporative Emission Control system stops fuel vapors from escaping from the fuel tank and fuel system. The EVAP system includes vent hoses and a canister containing charcoal for capturing, filtering and storing fuel vapors, and a valve for siphoning the fumes stored in this canister into the engine so they get burned off instead of being dumped raw into the atmosphere. It also has a pressure and or vacuum sensor for detecting small and large vapor leaks. When these sensors fail or there is a problem a code is generated related to what is detected by the ECM.Looking for a leak can be accomplished with a special smoke machine if a leak isn’t obvious and a High end bidirectional scan tool can make finding a leak many times easier.


  3. Causes of EVAP codes ( most common)

    1. Loose gas cap or bad gas cap gasket

    2. broken, disconnected, cracked, leaking, missing EVAP line

    3. Malfunctioning purge valve solenoid

    4. cracked and or damaged canister

    5. crack or damaged fuel tank

    6. line or solenoid valve clogged up with rust or debris

    7. bad o-rings or gaskets

          8. Evil car Gremlins