The code is usually the lot number. Here's how it looks on my Stress Coat:
EXP 02-2014 (with the date printed directly below the lot)
On my AquaSafe it's printed:
Ch. -B .418410 11/13 (the expiration date is the last four digits separated by the slash so 11/13, Nov. 2013)
So basically, the expiration date will almost always be the part of the code mumbo jumbo that has a slash in between it and most likely at the end or below the lot number. And look for the last 2-4 numbers to coincide with year numbers like 2013, 2004, 03, 13 etc.