check engine light code p1780. what does it mean?

http://engine-codes.com/p1780_toyota.html Park/neutral switch malfunction

http://www.obd-codes.com/trouble_codes/toyota/ ........agrees, go to either site for causes and solutions

I have a 2003 Tundra access w/stepside. I have replaced my gas cap seven times over the last 10 yrs. Always the code reads small emissions leak. They have given me discounts ( here and there) depending on the clerk. No where has Toyota admitted to a recall. I would buy several at a time. But, my hope is that they will get better.(LOL) The last one I bought was 9/27/13. The clerk told me it was the Japanese version, and, that it might be better. I doubt it. After replacing w/new cap, the check engine light will go off by itself after about 60 miles. Or you can have a tech reset it. Advance would not reset it for me.