Hello,
  I have a 1998 Nissan Maxima SE with approximately 75,000 miles on
it.  The check engine light on my dashboard is illuminated.  I took my
car to a mechanic who ran a diagnostic test.  The test said that the
problem is a loose gas cap.  I purchased a new gas cap and the
mechanic reset the onboard diagnostics computer.  A few days later the
light came back on.  I took the car back to the mechanic and he ran
the diagnostics again with the same results.  Clearly the problem is
not a loose gas cap.  I have read that the problem could be a small
hole in one of the hoses for the fuel system.  I would like to know if
the fuel system hoses could be causing this problem and if so,
approximately how much it would cost to fix this issue.  Are there any
other problems that could be causing this to happen?  This is a major
problem for me because I live in Chicago and need to pass the
emissions test or they will suspend my drivers license.

Thanks for the help,
Billy