check engine light on... car runs normal... just needed to get the new o-ring on and new vacuum hoses.. what could be the problem of this? because after work i came home, then took off to pick up my sister then it turned on?.. any ideas car has 87xxx mileage on it.. hks exhaust, intake, and koyo radiator on mods.. thats it.. any clues?

 

Pull the codes and see what you got: http://www.fd3s.net/engine_codes.html