Question about CEL

[ultimate1]

Hey I hate to put up another CEL thread. I just replaced the spark plugs, fuel filter, oil filter, air filter, changed the oil and differential oil a few days ago. My mechanic told me that I have a very small oil leak coming from my oil pan but not serious enough to warrant fixing it right away. I am driving back home from the bar I watch football at this evening and my CEL started flashing for a few seconds and then it went away. It started flashing again as I pulled into my garage and then it stayed on. I know I have to get my mechanic back to plug in the diagnostic tool to see what code comes up but I was wondering if any of you might have an idea what might cause the CEL. All the work recently done was for the 90,000 service.

Thanks in advance!