Guys, what are the causes that will make the engine light to lit up?

I just found out today that my check engine light is not actually on when i turn the ignition key to second position.. im guessing that the bulb went out.
If there's something wrong in the engine (like misfiring maybe?), can you feel/hear it? I'm just worried as I don't know when my check engine light went out.

about a month ago, the car was diagnosed by the SDS, and everything seems to be working normal, if the engine light was on (something wrong in the engine), will it show up in the diagnosis computer?

Maybe i'm just being paranoid, however I will bring the car to the dealer tomorrow to have it checked and the bulb replaced. I know i can probably do it myself from the WIS posted, but I'm afraid I dont have the confidence to do it myself...   

Ok.. just an update..

I went to the dealer today, and they said, all the engine lights for 112 engines has been turned off due to the fuel quality we have here. If I want to turn it back on, then they have to reset the ECU.

I live in Indonesia. Our gas quality was not that good, but I guess it's gonna get better now that they allowed foreign companies to sell gas here. We now have Shell, and Petronas (Malaysian company) here so far.. more to come i hope. Before that, we only have one gas company run by the goverment, so we didn't have a choice but to buy gas from them.  Now that they have foreign competitors, they have been reportedly upped their gas quality..

The SA also shown me the other ML that was being serviced there, apparently all ML320s, E320s for Indonesian market has their engine lights disconnected from Germany (or US for MLs) due to the gas quality here.

Well at least now I know for sure that its not the bulb :D 

 Ok.. this might be a stupid question.. but how to get the codes read off the ML?

If it's possible to hook up my own laptop to the car, what is needed to connect my laptop to the ML?

Thanks :) 

I'll look around see if I can find it locally.

Thanks guys