Air Filter head fell off! Check engine came on!

[Syroyizhka]

I was driving today, and my air filter Head came loose and fell off as i was pulling into the driveway, i picked it up, the mounting wasn't damaged ,so i put it back on, as soon as i did, my Check engine light came on, did something get into the engine that quick? should i bother taking it to Auto zone to get it reset, or should i just remove the battery terminal? the component doesn't look damaged, just scratched! any suggestions would be nice...

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After cutting power from the car for about 8 minutes, the light dissappeared, today i was drivng from work and it went back on!!!I'm really pissed, autozone won't turn it off, does this mean theres possible damage to the sensor? where is that sensor at? what should be my next move? (other than taking it to the dealer, f. that.)