Nissan Repair: emission control malfunction light, shary, emission control

Question
I was driving my quest'04 and the engine service soon sensor turns on, what could be? The car is almost 3 months that I bought it.(pre-owned) please help, before I go to the dealer I want to be updated with information.

Answer
Shary,

If it is an 04 and it has under 36K you are still under warranty and the dealer will take care of it for free.  If not, go to Autozone or Checker and they will read the code for free...  Then, email me back and we can discuss.  Now, if you just want to know what the code is before you go to the dealer go and get the code read, email me back and we'll discuss what you need to tell the dealer.