Toyota Repair: 2005 4Runner lights on dash, purge valve, charcoal canister

Question
My wife's 2005 4Runner has the check engine light on, which it seems has caused three other lights to come on as well.  I have read the forum about this issue and have had the error diagnosed as P0441 I believe.  I think it said Emmissions or evap error or incorrect purge.  When I looked up the code. My mechanic replaced the gas cap but used a non-authentic toyota part.  Fail.  I had an actual toyota cap put on by a different mechanic, lights went out for a few hours then came back on.  I unhooked the negative side of the battery and let it sit for 30 min, this cleared the lights for one day but they are back now.  The testing and diagnosis and gas caps are getting expensive.  Please let me know if you know what the cause is and if there is any real danger to the car.  It has driven fine with the lights on for awhile now.  Also please let me know any other tips I can try myself before taking to the garage yet again. Thanks so much!

Answer
Without doing certain evap system tests, I can only give you the most common sources for this code, the evap purge vsv ot he evap system canister, the purge valve is located under the hood near the air filter nad has two large vacuum hoses going to it and an electrical connector, locate the hose with the green valve on it, it goes to the fuel tank, the other end goes to the purge vsv, you can try replacing the valve and if that's not it replace the evap charcoal canister.