Secondary Air Pump
 

A secondary air pump on my Mercedes kicks on even when the engine is warmed up and It keeps working even when I stop the engine. I unplug the socket every time it does not stop. First time, when I did not know the reason I had to take off the the battery. However, it does not happen always, only once in while.
If anyone happen to know the reason of this problem, I would appreciate the advice. Technicians does not have an idea what that is. The error code appears on it is PO-410. Please, give me some advice.

Hey ive a A class 51plate that does exactly the same thing. Ive also had a mechanic look at it and not know what the problem is, though mine didnt give a fault code.
if anyone can help with this it would be very much appreciated

thanks