P0410 code secondary air injection problem could be the secondary air pump ground, blue check valve on the pump or most likely the RCM has a bad relay in it. The RCM is $125 to $180 for OEM Mercedes part online.
One of the members Tigh1 rebuilds RCM's for around $25 or so. Search forum for RCM relays and you should get all the correct info on the problem.