Mike,
The check engine light will only not come on when the car wont start.
The k 40 relay is the relay that supplies most of the control units with power.
The stand alone key does have a transponder in the plastic part.
It was a joke that it is a male key,because if you hold it blade pointing down,it has balls!

__________________
Mercedes Benz Master Tech
ASE Master Technician
Diagnostic Technician
Owner of "Behind the Star Inc."
Raleigh NC.
www.behindthestar.com
brian@behindthestar.com