I needed some help if someone had a similar problem. My m5 is due for a smog test an i went today to a test only center after plugging in to his obd2 computer the state scanner notifys smog station that engine light is on. Although my display doesn't show a engine light. Also during initial engine start i dont get a engine block to be displayed an shut off it never crossed my mind. The smog station computer said catalyst system low level efficiency he cleared the engine light an told me to drive car so it can be smogged the following day after 40 miles. Well i was wondering if anyone can give me any pointers if it might be my aftermarket stereo equipment, afe intake, headers, muffler? I do have stock cats! Any help is appreciated. Thanks