Perfect car sat idle for 3 months. Now check engine light blinks yellow? Why?

What is your question?

I bought a new Mazda so I parked my Suzuki in the garage. It was last driven regularly in February. When I started it last week and drove it, the yellow check engine light came on and started blinking. What could cause this since it was running perfectly before I parked it? Could the oil or gas have gone bad or settled? Any help would be appreciated.