Hi. I Have a 2008 chevy cobalt an the check engine light just came on. I went to advanced auto parts to have them diagnose it. the employee said it was a "smog filter" . I admittedly know very little about cars an thought I should check here to ask what people think of this diagnoses an is it a real threat to my vehicle

What was the actual code number that they pulled? This number will allow us to double check their diagnoses.

P0411 secondary air injection system / Incorrect flow detected

http://www.obd-codes.com/p0411 --- check this out for possible causes and solutions. Hope this helps

thank you very much for the info.i appreciate your time