There could be many different reasons, but the only way to know for certain is to get a mechanic to take a look at it. You can check out driverside.com (http://www.driverside.com/servicing/Hyundai-santa_fe-2001-3383-7061-0) to see if there are any users with the same problem, and also find a mechanic in your area.
If the check engine light it on a 2002 Hyundai Accent on one of the sensors is malfunctioning. The computer is acknowledging this and alerting the driver that there is a problem in the engine.
I have a 99 Hyundai Sonata That the check engine light came on, and # 3 & 5 Injectors were fouled
it has a problem
No the check engine light will not come on
The computer has detected a problem with the emissions system. Take it to a professional.
The check engine light, on your Hyundai Elantra can be reset by removing the fuse. Keep the fuse out for 10 seconds and replace it to its slot.
you disconnect the battery for a couple minutes.
P 0172
Check your gas cap. Lots of times its not on tight and causes your light to come on. After you check your cap remove your negative battery cable for a minute to clear the computer and then see what happens
There are dozens and dozens of causes for the check engine light to stay on. You need to have the computer checked for codes to know possible causes.
No
The engine is overheating. The check engine light is not on because you have no problem with the emissions system which this light monitors.