Toyota Repair: Check Engine Light, air flow meter, phillips screws

Question
1999 Toyota 4 Runner Limited with 6 cyl engine and auto trans.  Today coming to work my check engine light came on and I went to AutoZone for a diagnostic check.  Came up as a P0171, something to do with a sensor but they told me to go to my dealer to see what had to be done.  What does this really mean?  A sensor?  If I leave it as is what will probably happen?  They said it would be about $125 or more at the dealer.

Answer
I'm going to give you instructions on how to fix this condition but you must follow them exactly if you want to do it yourself or you can have a repair shop do it.
The problem is the volume air flow meter located just behind the air filter in the intake tube, it is attached with two small phillips screws, remove it and clean it with an electronic parts cleaner(do not use anything else) spray the cleaner inside the openings in the air flow meter to clean the platinum wires that sense the air flow, let it dry or blow some low pressure compressed air to dry them.
If this is done correctly it will fix the problem, after that , pull out the EFI fuse in the fuse box under the hood on the left side, wait 10 secopnds and reinstall it and the problem is over.