Most dealerships warranty work you that you paid for, for a set period of time/mileage 12months/12,000 miles, or 24 months/24k whichever comes first.

But most of the time if you didn't pay for it (went though a warranty) they will only warranty it though the end of the warranty period. For example, if you had work done 1 month before the end pf you warranty, only warrantied for 1 month.

If you are still with in the terms of you extended warranty, you should be good.
No idea how the deductible will work out if your extended warranty has one.

Be advised, just because your check engine light is on or oil is leaking doesn't mean is the same failure or the same problem and will be covered under warranty. There are hundreds of codes and multiple places for oil to leak from.