2001 Volkswagen Beetle Check Engine light

My wife's New Beetle has the Check Engine light on and we are in a very remote area of Colorado, we don't have any qulified mechanics in the area who are familiar with the Beetle. Can you advise what the most likely cause is. The car does not have the low end power that it used to have, by the way it is a turbo model. My old "shadetree" guess would be O2 Sensor, if you agree, I don't even have a clue where it is on this vehicle to change it... With these newer cars I have to admit that I am the "village idiot"...
Thank you very much in advance.
Mike Warrick