im stumped with check engine light

[MasterMyers]

my check engine light has been on for a couple of days i not been able to get a appointment at the garage i bought the car from to get them to work on it since i have a warranty but tonight i noticed i can hear a small hissing from about under the shifter (this is automatic) for a few minutes after i shut it off, i thought maybe a hose i cant see unless it was on a rack was cracked but i can also feel vibration under my feet and some against the gas pedal when im driving, i cant get my car into the shop until tuesday, any dieas on what this might be and how serious it is, ease my mind.
thnx.

[MasterMyers]

got it checked today there was a small screw stuck at a angle in my tire, yanked it out, it didnt puncture anything. the check engine light went off