Worked on a 1999 camry today ( early evap system ) with the very common P0441 - P0446 codes. When de-energized the vapor pressure VSV connects the canister side of the system to the vapor pressure sensor. When energized it connects the tank side to the pressure sensor. With the VSV de-energized monitor the vapor pressure sensor voltage, now remove the gas cap , if the voltage changes the VSV is faulty.

Tom from Illinois