Ford Repair: mustang, pvc valve, auto parts stores

Question
hello again steve, after my cat question i was just starting my car and talking to mygirlfriend before i left her house and i looked down and i noticed my "check engine" light was on, the only thing i have done to my vehicle is cut some of the cone off of the air filter to allow more flow, but i did that about a month 1/2 ago, wouldn't that have set it off shortly after i did that, could that be doing something, or is there a common problem that you know of, that could have, just out of no where set that off, also, would my pvc valve have anything to do with it, it kind of worries me....

Answer
Andrew-

  While cutting the filter is definitely not a good idea, I'm not convinced it's what caused your problem.  It's a lot easier to just use a high flow air filter rather than cutting one up and risking loose pieces making their way into your engine.  Really the only way to know for sure what's causing the engine light is to use a code reader.  A lot of auto parts stores will do this for you for free so there isn't necessarily a need to pay a shop $60+ to do it.  It's unlikely that your PCV valve would be causing the light.  PCV valves can cause lots of problems when they clog shut or stick open, but 99% of the time this won't cause a check engine light...just some headaches.  Hope this helps.

Steve