Hyundai Repair: Start Problem 2000 Elantra, crank sensor, trouble code

Question
My daughter's 2000 Elantra has normally been running fine, but twice now it has exhibited a starting problem.  It cranks fine, but won't start - doesn't even sound like it's catching at all.  On both occasions, after about a 30-45 minute delay it started with no problem.  I get a check engine light, but when my mechanic checks for a code, he gets nothing.  The light went out by the time I got the car to his shop.  I don't want to start replacing things without some clue as to the potential problem.  Any ideas?

Answer
I'd suspect a crank sensor, but this is just a guess at this point.  To be certain, the mechanic will need to be able to test while the condition is occurring.  In most cases, if there's a trouble code, it usually enables a very high percentage of fixing the issue, even if it isn't happening at the time.

If your check engine lamp was on while the car was running, the code should remain for at least three drive cycles, even if the lamp has gone out, unless the code was cleared.  If the battery wasn't disconnected or drained prior to the mechanic checking the car, he should have been able to retrieve the code.  I'd suspect that his tool may not be able to properly communicate with your car.

Additional follow up from question in comments:
I don't recall the question you're describing, but if the issue is intermittent, it's pretty much impossible that it's caused by a fuse.