Toyota Repair: 2002 toyota avalon xl, check engine light just came on, toyota avalon, diagnostic fee

Question
I have a 2002 Toyota Avalon with approximately (v6 engine) 125,255 miles on it(when I purchased it, had 84, 302 miles on it), my check engine light just came on today, I have checked my oil and that is fine ( I am over with my oil change, need to get that done)I have also checked my transmission fuel and coolant and that is okay, I have had the car for 2 years this June, and have yet to get a tune up, and I also notice that where the oil goes, there is what looks like a build up of oil, what do you think the problem could be as to why my check engine light is on?

thank you in advance for any assistance that you are able to give me.

Astria

Answer
The check engine light is on because there is a malfunction with the engine control system, the first step is to retreive the trouble codes stored in the onboard computer, the toyota dealer and most repair shops may charge a diagnostic fee for this but some of the larger autoparts retailers like autozone do this at no charge, after the codes are known let me know what they are and I can be of more help.