today i went and filled up my 05 wrx. i usualy put in 93 octane but all i could find in pa is 92. i get back into my car and notice that the check engine light is on. i have no idea wat could be causing this. my friend told me that it could be that i didnt tighten the cap well enough but i went back and checked and it was on fine. any ideas wat this could be caused from?