Toyota Trouble Code P0446 - EVAP (Evaporative Emission System) purge/vent solenoid circuit condition. Your Toyota Camry EVAP system has a pressure sensor to detect if the tank remains pressurized while the EVAP monitor is running, basically ensuring it is not leaking. If the fuel tank depressurizes during the EVAP test, a trouble code(s) is set indicating a vapor leak and/or a defective EVAP system component(s)
The probable faults to look for include:
1.) A defective purge or vent solenoid(s)
2.) Insure all sensor and solenoid wiring is connected and not damaged
3.) Check for a fuel saturated vapor EVAP canister
4.) Check for a damaged or defective EVAP vent solenoid
To start we recommend you check all hoses to the charcoal canister and VSV system. Your Toyota's charcoal canister could have a leak which will not allow proper pressurization of the gas tank, and/or a defective VSV for pressure sensor or vapor pressure sensor. Should you choose to replace the Charcoal Canister, it will be equipped with a new Pressure Sensor and Vent Valve.
