Check engine light on Mercedes Benz SLK 230?

I hope you have better luck than I. I went to Advance Auto Parts, and had one of their techs to run the code on the computer. It was a "Secondary Air Injection Malfunction." In the SLK 230, secondary air is pulled off the supercharger, which in my case cost $3100 . There ARE many more codes, including a faulty gas cap which will trigger a "Check engine" light. I wish you well, and hope your code is a cheap fix. The dealer said mine was probably the worst one to have.