Chevrolet: 2000 Chevy Venture service engine light., chevy venture, service engine soon light

Question
I have a 2000 chevy venture and the service engine soon light comes on. Can you provide me with some possible reasons this may be happening? The van seems to run fine. The idle seems like it may be a little off sometimes but thats about it. Is there anything I could check on my own? They want about $80 just to hook it up to a computer to test it. I think that is a little excessive.

Answer
James;
 The light comes on for a reason,  the parts that are hooked to the computer and to the light are set to factory specs , and when the parts like sensors and filters , valves ,etc, are worn or dirty they get out of fact. specs they then    send to the computer to the check engine light because something is out of the happy medium settings.this is to keep the engine and parts from breaking down alltogether and than you would be stuck - so the light warns you , some of the reasons are a bit far-out as if the gas cap could be on wrong - some cars this will cause the light to come on so there are reasons for the light , if the car is running fine I would let it go till you have the time or when you see that the car is running rough .or if there is a special for 29.99 to have it checked than take it in , as long as it is running good - take your time but keep a eye on it  ok.