Nissan Repair: 1997 Nissan Sentra GXE, nissan sentra gxe, nissan sentra

Question
For three years I have had a check engine light that only comes on when its warm outside. I had it read and its a code for evap in the fuel tank. Other than that it could be one of about 4 different parts, they didn't know what to tell me. Nissan said they could accurately diagnose it, but i'd like to avoid paying $110 just to find out whats wrong with a 10 year old car with 120,000 miles on it. I assume it's a seal somewhere. Is there any way I could narrow it down on my own without paying someone to do it? Thank you.

Answer
Audrey,

It could be as simple as a gas cap being loose, a rotten fuel line or a loose hose clamp.  The evaporative system is closed to the atmosphere and any leaks will set the code.  So, the $110 to diagnose would be worth it if it involves taking the gas tank down to see what the problem is.  Now, you could get lucky and it would only be bad gas cap.