If you are like most of us, at some point you have been in your car just as happy as you can be and then all of a sudden....BAM, your check engine light is on and of course your immediate reaction is something serious has just happened to your car; well, not necessarily. The check engine light can come on for many different reasons and it might be something as simple as a loose gas cap. Basically, the check engine light is linked to your car's on-board diagnostic system which measures everything from engine speed to gear shift timing. In many cases, if the light is on without flickering or going on and off, chances are the problem is minor, but if the light is flashing rhythmically that could be something much more serious which is why you need to pay attention when it comes on. There are several things you can do on your own to potentially diagnose the problem before you pay big money to have a mechanic look at it. The first thing you should do is read the owner's manual to understand why the light might come on in the first place and go from there. Click here for some tips that might solve your problem cheaply from yahoo.com.