Thanks for the reply. Is there a separate air pump on the slk or does the supercharger act as the pump? Which is considered primary vs secondary? I've read many of the posted threads on po410 and air injection, and it looks like there is no clearcut method to diagnose the cause of the error code. Can anyone suggest the order in which I should start, besides the cheapest one first. The car starts and runs fine. There is some hesitation when I floor it. Cold start is no problem.

Thanks
Bob